Well, this is my 3rd post on thirdgen.org, with the first to being no start problems that have since been resolved. Now I am having a problem with the car running very unevenly with no power. I have replaced the iac, cts, plugs, wires, distributor cap, rotor, oil pressure sensor, water pump, fuel filter, ohm tested and replaced bad injectors, compression tested, fuel pressure tested. My 89 Firebird tpi 305 will start up without starting fluid (wouldn't before) but now it revs from 450 rpms up to 1000 rpms and then right back down and keep doing this steadily until I shut the car off.

I have tried disconnecting the ecm and battery and waiting 5 minutes to re-connect to see if that helped but it didn't. Could the revving be due to a vacuum leak somewhere? It sounds like it is sucking air, then getting extra gas to balance it out. Any suggestions? Thanks in advance.

 

Have you adjusted the TPS? It could also be the Mass air flow sensor, while it is running tap it with a screwdriver handle, if it changes the idle there is your problem.