1987 Toyota Supra Idle

[spycialost9999]

My Supra 5spd 3.0 non-turbo idles from 1000rpm to 2000rpm, back and forth. Doesn't matter if in neutral(no gear) or what temperature the engine is. Could this be the air flow meter, idle air control valve, or throttle sensor? Cleaned around all the spark plugs and replaced with bosch platinum quad tip. The idle air control valve had alot of carbon so I cleaned that also. Checked for vaccuum leaks, could not find any. Vehicle runs ok on highway, but when in idle it just goes up and down from 1500 to 2000rpm. This might be important, I broke the BVCV that is attached to thermostat housing, would that cause me my problems. Also, I just replaced the power steering pump amd am wondering how important is vaccuum hose connection? Last thing-the fuel gauge sometimes reads empty even though its full. All the other gauges working.