Hey all relatively new here.
My Monte is 02 3.4 LS it's almost made it to 175k miles.

Recently i've had a lot of work done to it. I had to replace the wheel bearings, and when i took it into the shop, they noticed the coolant looked like it had gunk in it. They drained it and refilled. This started a flurry of cooling issues. I bought a new radiator, then water pump, Replaced all the hoses. Finally the Car ran well for a few days. Then it over heated again, the Lower intake Gasket went and started eating coolant. So had them fix all that. Also replaced the Thermostat.

So here i am about 2 months later, and the car atleast has no cooling problems. My Gas Mileage has fallen from around 28 ish to 20. The car idle's okay it gets through lower gears just fine. But if i give it anything over half peddle the car doesn't have any power. When i was sitting it in idle, i revved it up and as soon as i got over half peddle, it started dropping off and jumping up again. I'm assuming this is a TPS, but the only computer Reading i have is for an EGR valve i need to replace. Do you think this is the cause or have you ran into anything else?

 

Could be a clogged cat.

 

Idk what your egr looks like but early 90's gm egr valves could be taken apart and cleaned with carb cleaner most the time resulting in success. I also like chibi's post, check the cat before you replace egr

 

fuel pump. my old lq1 lost power under any acceleration. could only produce like 15 lbs of pressure tops. fuel pressure guage sure beats messing with a cadillac converter lol

 

I wouldn't want to mess with a Cadillac Converter on a Monte Carlo either! :p

It's Catalytic

 

Well i had my mechanic check the TPS first since it is fairly easy. Sure enough that was going bad. So i replaced that. But Wouldn't you know it the problem still exists. The voltage of the TPS shows correctly. I will have them check the fuel pressure and the Cat converter Next.

 

Good to hear the update, after the cat is checked then take care of the egr if its still a problem.

 

Based on your info, let me through something else to just check out.... All this seems to have happened AFTER getting the LIM gaskets done....

- Check for a vacuum line not connected (if it idles fine, hard to say that's the issue)
- Ensure the tunnel on the UIM for the EGR is gunk free. It starts where the EGR sits and goes to behind the throttle body. Some carb cleaner in there and work something like an old speedo cable in there until it goes all the way through.
- If it has NEVER been done, change your fuel filter. If it has an obstruction, it may be making it difficult to deliver fuel.

Outside of that, these symptoms suggest what others have suggested. Clogged cat or a problem with fuel pressure.

Keep us updated.

Welcome to the forum.

 

I'd bank on the fuel pump. If the cat went bad you would probably have a CEL come on due to the second O2 sensor giving improper readings.

 

Not always, when my cat clogged I never got a CEL. However when I put the new cat on I got it lol