Car is a 1992 Camaro with a 305 engine and TBI. Engine starts OK when cold but has a very erratic idle (500-1500) and occasionally stalls. When I try to drive it it surges forward from a stop almost dies and repeats this routine until about 40 MPH. The idle smooths out a lot when warmed up and runs better but still studders a little when the gas is depressed. The vehicle has a new fuel filter. It also shows 17" of vacuum when warm. I spayed carb cleaner down from the top into the IAC opening with the engine running. The injectors look to be spraying OK and both about the same. I am at a loss of what to do to fix this problem.