I have a 1991 RS and starts up great, but when it warms up and closes loop if I give it the throttle the engine boggs down and wants to quit running. It does not show any codes and when I hook up a Vacuum guage to it, it holds a steady 20 on the guage. Need help figuring out what is causing this problem. Any ideas Please. Sorry I forgot to put in that it is a 305 TBI. By the mechanic of the previous owner it has had all new sensors placed on it and new fuel pump.

 

305 or 3.1? Based on what you typed it is either a flow issue or a timing issue. Flow could be limited air flow in, limited fuel flow in or limited exhaust out. Timing could be spark timing or valve timing

That covers a LOT of possible problem. Fuel pressure test might be the first thing I would do and exhaust back pressure next. If you have a scan tool you can check to see if the MAP and air temp sensors are reading right. Is this a engine with a MAF sensor?

 

I had similar issues, but i got a check engine light on my 90 RS.

It was the EGR valve. Try that. Cheap and easy trial and error fix.

 

Thanks for the input I will give those a try. Thanks again