Hi everyone! I've been working on this problem for about a month. The car starts a bit rough but idles just fine. Once the car gets warmed up, I try to put it in gear and it sputters then dies. I've noticed that the coolant temp doesnt read on the dash. I just replaced the CTS with a known working one from another car. Could this be a fuel problem? I disconnected the IAC valve and the car wouldn't start at all. I also noticed that the fuel pump makes a loud humming noise. There is also a vibrating sound comming from the fuel distributor that comes on and off about 2 seconds apart. I just replaced the fuel filter in the engine compartment.

Can anyone please help me? I'm loosing my mind!

Thanks,
Josh

 

Clean the IAC and try again..

Also check all the vacuum lines. My 89 200QT acted like that and I finally found a split vacuum line.