Bought a 1991 RS 305 TBI it has edelbrock in take, headers, and a chip for the ECM. Car starts fine but has a slight miss as car heats up the miss will get worse and cause car to stall. upon hard excelleration when RPM gets high car start to miss bad and if driven on highway at high speed car will cut right off but engine stays running if I go below 50mph engine will come back to life. I have changed coil. distributor module, and distibutor pickup coil. I have also replaced the hipo chip with a stock chip. Car still runs the same. Could the ECM be bad? Bought the car for my son's birthday on Monday Need Help Please!

PS Friend put scanner on car had a EST and EGR faults. Friend believes EST was caused when we checked timeing
----------
ps the tach and speed-o go crazy when this happens

 

When you checked the timing, did you also adjust it?

 

Welcome aboard thirdgen.org.

Sounds like a distributor module or coil problem. I know you said you already replaced them, but the tach going wacko because of the ECM seems unlikely. Double check the wiring for an intermittent open.

So, his birthday is the 12th. Same as Kirstie Alley, Rush Limbaugh, Howard Stern, Joe Frazier, Tex Ritter, Hermann Goering, John Hancock, a certain TGO mod. . .

 

I would be happy to give you any help I can, i have access to any electrical diagram you may need.

 

May be catalytic converter going bad. Check for codes first.

 

just a thought-have you looked at the fuel filter? Does it look like it has been replaced?May also look at grounds on thermostat housing and back of the head.
If at all possible find a fuel pressure guage to use that you can view while you drive.

Hope this helps!

 

I would check the fuel pressure or atleast install a air/fuel gauge to see if you are running during open throttle. I was having some of the same problems. If it was just a timing issue, your car would still be able to drive without stalling ( unless you are way off on the timing).