when the engine is very very cold (ie, seconds after startup) if i just barely barely touch the gas pedal, the RPM drops, and the engine makes a louder ticking sound than the valves would normally. when i let off, the RPM resumes to a normal state. Is this normal functionality of IACV and TPS working together?

the ticking ONLY happens when the gas pedal is superlightly pressed, and the rpm is sagging from the high warmup idle.

that, and the ticking happens for the first 2 seconds of startup, i guess while oil is circulating up into the valvetrain. just during the initial 1700RPM spike after the starter is disengaged.

 

the gas-pedal-related ticking has been identified. When the throttle is nudged past the idle point, the TPS sends a signal thru the variable resistance circuit on the TPS (A/T only, right?) which does something and clicks a solenoid inside the tranny, at a fairly rapid rate. This ticking stops if i unplug the drop resistor, or if i unplug the harness connector below the IACV plug connector and toward the engine. Don't know what that plug actually connects to, but it's part of the A/T control harness.