Hey guys.

I own an 87 trans am with a bit of a mutt engine. It is a 350 vortec block from a 97 yukon with an 86 camaro tpi intake, and the computer has an aftermarket chip. I bought the car with this motor in it, and have recently been having some issues since I took it out of winter storage. Any help is much appreciated, I'm at a loss of where to start because there could be so many things causing the following issues and was hoping you guys would have some insight on common issues these cars have with over fueling.

My problem seemed to start after I got caught in the rain driving home one night. I don't usually drive the car in bad weather but as I said I got stuck. The next morning when I tried to start it it would turn over but wouldn't start... I ended up having to put the petal to the floor in order for it to finally cough and sputter, finally starting. Since then, every morning that the car sits all night or even when I let it sit outside during the work day it struggles to start without having at least partial open throttle. When it does start, if I don't hold the throttle open the rpms drop and it sounds like the car has a huge cam in it, dropping its idle until only one cylinder seems to be firing and then it finally dies. Over time, this problem has been getting worse... I have not been driving the car because I am worried about damaging the motor. Now when it starts you can hear pre-detonation of fuel and the motor violently shakes around so much that it is noticeable from those standing around and within seconds the computer throws a code 33... Even an open throttle will not stop this as it sounds like it is only firing on 3 or 4 cylinders at 2000 rpm. I obviously have not played around with this too much, as I said I don't want to damage anything. Also, when the car does start like this un burnt fuel collects on the exhaust pipes along with thick exhaust smoke...


Anyway, I have a good amount of experience working with cars but this is my first 3rd gen. I have checked the timing, tightened and replaced the distributor, rotor, spark plug wires and spark plugs. The new plugs became horrible and fouled within a week of diagnosing problems but it did run better for the first few days after new plugs until they too became fouled. I have checked the resistance on the temperature sensor and MAF sensor and have replaced the O2 sensors... One things I did notice that I wish I could check is fuel pressure as the bleeder on my fuel rail always is purging extra fuel, so much so that I have to wipe it off with a rag. I have not checked vacuum leaks yet but that will come tomorrow.

If there is any suggestions of things to check please let me know... I love this car and hate to see it in this condition. The problem is getting to me so much that I almost want to just buy a carb kit and go old school... Thanks in advance I really appreciate you taking the time to read all that. Cheers,

Deven.