I have a 2005 monte carlo ss (l67) and I can not figure out whats going on with it. Here is a summary of symptoms and what I've done, I appreciate any help/advice.

Symptoms

1 Car has been sputtering off and on the past few months
2 at idle the car will continue to run but shakes a lot and acts like its choking
3 There is a strong smell of gas now when it is at idle
4 The sputtering goes away when I step on it at idle or driving down the road
5 poor highway mileage 22 mpg max

Codes and failed fixes

1 new plugs (ac delco iridium)and wires
2 all of the above sensors replaced on the throttle body
3 switched out the coil packs
4 I do have K&N cold air intake as well
5 Throttle body cleaned and looks brand new now
6 hooked up a fuel pressure tester and get a 0 reading both on and off, but yet the car still runs???? really confused by this.
7 It seems like its running rich

I have had the codes P0301 P0300 P0201, And one a while back that said something about a major evaporation leak

 

if my memory is correct, the p0301 is cylinder 1 misfire , p0300 indicates random misfire and p0201 refers to injector failure, prob #1 cylinder.
if new quality plugs and wires didn't cure the misfire, id look at the injector(s). as far as fuel pressure, obviously it wouldn't run with 0psi so either the gauge is faulty or not hooked up to the Schrader valve correct. those evap leaks are usually impossible to find with the naked eye. a smoke machine works wonders to find those buggers. a common place to start is the gas cap and cheap.

 

Totally has all the characteristics of a failed fuel pressure regulator...

 

I would agree with that, and you didn't mention the Fuel filter being changed you might want to consider that also.

 

Pull cylinder 1 spark plug and see how it looks. See if it's wet etc. Another thing to do is swap cylinder 1 injector with another cylinder and see if the misfire follows that injector. I also suggest replacing the fuel pressure regulator. Last thing, I hope you replaced all sensors, coil packs, and wires with acdelco parts. The China crap that's cheaper is just that.... Crap. It's given many people issues here in the past.

 

I agree will all of the above and would add the likelyhood of a vacuum leak which would account for P201, large EVAP leak, but that could be the FP regulator. I would start with that, but there might also be a leak on one the of the EVAP lines or components, or the UIM might be leaking from a gasket or a hole melted through the plastic wall of the "stovepipe" where the hot EGR gas passes through.

 

so I pulled my fuel rail and and decided to replace the fuel injector but I am waiting on a rebuild kit for the plastic retainers so in the mean time I tested the ohms and all of them read 11.8 except cylinder 1 which read 11.5 I do not know what this means.

Also I took pictures of the spark plug that came out of cylinder 1 as well one picture with the spark plug by itself and one side by side with another spark plug. Also, these only have 30,000 miles on them. My car has 133,XXX. I really appreciate the help

 

Ditto on that.

The fuel pressure regulator is the circular object in the middle of this picture, just to the right of the engine:

 

The ohms being a couple 1/10s different wont make any difference, at least you know you are getting juice to them at least. That injector could be stuck open, barely spraying or a dozen other different things. Changing it out wont hurt a thing.
Ive personally not had any issues in my travels with the fuel pressure regulator but others apparently have ran into that before so id have to give it consideration also. Id suspect it has a diaphragm in it and could be leaking.
I hate just guessing and throwing parts ***** nilly at something. But if you don't own a scanner with live data stream that's hard to do.