I have a 1987 Firebird with a 2.8L and the 700R-4. When it is first started it idles so low that it stalls unless you pump the gas to keep it going. Once it warms up the Idle keeps increasing the warmer it gets all the way up to 4000ish, maybe higher but we shut it off around then. The transmission was changed recently and after that it overheated because the fan did not turn on. That's when the idle problem first started. We direct wired the fan to keep the motor cool and I have changed from a parts car with known good parts the fuel injectors, fuel rail, new fuel filter, the throttle body, thermostat, all the sensors on the throttle body, the distributor, the plugs, wires, cap, rotor, coil, cold start sensor, and the MAF. Also I checked all the vaccum lines for leaks and changed the intake manifold gaskets. The problem is still there and can't figure it out. The timing as also been check a few dozen times and there is an exhaust leak on the headers pretty bad. Would that leak cause it? or Could it be the O2 sensor? Those are about the only two thing I haven't done yet. I checked the compression with my finger in the plug holes, would that be enough to tell if the head gasket is blown? Could it be a head gasket?