My Firebird has been sitting for about 4 years. Drained the tank, new fuel filter, fresh fuel plus additives, new plugs, new pickup coil, rotor and cap, installed throttle body kit. Everything I've done has helped a little each time. Will now start but I have to continuosly pat the gas pedal to keep it running. Once it warms up a little it will idle on it's own for a few minutes but while it's idleing it's going up and down from 500 rpm to 1500 rpm. Tried a known good used TPS but that didn't seem to help. Could the injectors be clogged, the AIC be bad, vacuum leak, WHAT?