I have a 2000 monte carlo with a 3.4 and it takes a little throttle play to start if it does and run rather rough.. at idel its either to low of rpms or too high i mean like maybe almost 2000 rpm. There is a pretty noticeable stall if you step on the car at idle and sometimes die. Any info on whst that may be possible tps? Iac?

 

I assume no unusual exhaust smoke? Assuming no unusual exhaust smoke, no engine codes and that it's above 100,000 miles it may just be in need of some basic maintenance.
If you have engine codes, go have it scanned and report back, reading the below info is of no value until we know the codes. If not, keep reading:
- If it's the factory CAT, have it inspected for failure! 2000 and 2001 GM had a horrible bad run on cats. If you have the car running for a few minutes, look under and see if the cat is glowing red, if so, 100% change the cat, otherwise, get it checked.
- Change plugs and wires. NO BOSCH plugs. NGK and AC Delco are you best plugs (all my 3100 and 3400s have ran NGK platinums from RockAuto and no issues).
- Check for vacuum leaks
- Change the air filter
- Change fuel filter
- Remove and clean carbon crud from the IAC and if you are adventurous, pull the throttle body off and clean the back side of it.

Hope this helps (BTW - those steps are in order of what I think is most likely to least likely).

 

okay I had them checked yeesturday should have said something
I had 3 codes
1 maf sensor- only because it seemed to run better without it so I had unplugged it now if it was there prior im not sure
2 coolant temp sensor- I replaced that but the gauge does not work still and the fans seem to be on a majority of the time. as well it seems to run a little weird with it plugged in. not sure
3 wheel speed sensors hence the abs light.

I smell CAT at times but I throw no oxy codes.
I used MAF sensor cleaner on the IAC the TPS and MAF with a small difference now it idles high with a hesitation.

I Usually like AutoLite platniums that's what I bought for it. plugs say delco so I assume orig. and it seemed to have a slight miss idk if that in coralation to the IAC TPS or MAF but im not sure.

it has 94,xxx miles

I don't think I hear a vac leak but not sure haven't investigated to hard just worked around the sensors.. also replace the black air filter and fuel filter is next.. I just bought it for a good price so I figured I could come out but no head issues or coolant issues so far..

Sorry that's so long

P.S. no exhaust smoke althou it has a slight blackening around the bumper.

 

I would change the plugs, definitely at that mileage and not even think about it. Some have used AutoLite (I have no experience with them, nor have I heard anything bad).
As for a vac leak, you probably WON'T hear it. Mist starting fluid while the car is idling, focus anywhere you know there is a vac line/connection. If you have a vac leak, the mist gets sucked in and the the idle changes.

As for the codes, what are the code numbers??? Sometimes there is more to them then simply a small item.

 

Engines run like **** for a few reasons. The most common are in no particular order too much fuel which causes backfiring and rough idle and you'll probable smell it. Not enough fuel and your car will want to stall. Too much air like a vacuum leak and you'll get a high idle. So you can spray starter fluid around the motor to see if I revs in the case of a vaccum leak. This will point out a leak. Next you can tap the injectors to see if they're clogged in the case of not getting enough fuel. Sometimes twisting them helps. And of course a misfire.

There's a starting point for you anyway.

Your getting close to 100,000 miles so like suggested above you could go ahead and do a tune up i you havnt. Spark plugs, pcv valve, air filter, fuel filter. A good oil change would be good too. But go ahead and put a good quart of marvel mystery oil in for a few hundred miles first. Ive seen that **** work. I ripped apart a motor and cleaned the inside with some marvel and a rag and it didnt take much to get that baby lookin like brand new. And that was a motor with 150k.

 

Ok kool ill check that out i did find a line that comes off the air intake between the intake and the mad sensor its a plastic tube where could it run to?

 

The tubes running off the throttle body? That tube i believe leads to the fuel pressure regulator which reads how much air is coming in and adjusts the fuel accordingly, and it also goes to the purge valve which i believe sends back vapors to the fuel tank. I believe sometimes a clogged fuel pressure regulator can cause bad performance but i think its rare so tackle the other stuff first.

 

If that's the tube I believe, it goes from that air duct to the back valve cover. The grommet that holds it on the back cover often gets disfigured so the tube won't hold in 100% or it won't have a type seal. This is related to the PCV venting system. My experience is that it's not 100% mission critical if it's got a tight seal, you won't have a problem, but it if highly recommended you have it connected the way it should be.

 

Fuel pressure regulator could be the problem, do yopu smell fuel? It could be dumping and running way rich.

I had replaced mine 3 yrs ago when I smelled fuel and saw fuel leaking from it. Just last summer the monte was running ruff again and stalling alot to the point it would not start. Misfire codes were thrown and one other that I do not remember. I found no vacuum leaks and replaced fuel filter. I never thought of the fuel pressure regulator seeing as I just replaced it and I was stuck taking it to the dealership. They ran a diagnostic and found it was running rich. The dealership replaced the fuel pressure regulator and problem solved. I was pissed because this was easy to replace and dealership price was high. I must have used a cheap aftermarket regulator.

I think it is a $50-$60 part

 

im currently running auto light platnium in mines and no problems