On the back of the tb42e intake, there's 2 solenoids. Excuse me if I get the names wrong but one is the aac valve and the other is the fast idle compensation device or something or other. I know the fast idle solenoid makes a click when the aircon is turned on to compensate for the extra load placed on the engine. Is this the click you could be hearing?
Pull the entire valve assembly off and give it all a good clean with some good carb cleaner. There's a spring and plunger that the aac solenoid operates, ensure this operates freely. Also the plastic adjustment screw, unwind it and give the oring a moisten when vasoline.
As well as doing this, my 2nd step would be pulling the tps off and testing it with a multi meter for correct operation. It's mearly a potentiometer in a plastic box so test the resistance of it and ensure the resistance grows/drops continuously without any open circuit conditions, if that makes sence.
If all good, install it again and set it to the position it needs to be in, then go from there.
Pull the aac plug off and using a timing light ensure base timing is at 10degrees btc. Adjust if needed.
Run a tank of injector cleaner. I've used fuel doctor and it seems to work.
I've got the same engine and I had the same saga with trying to get it to idle properly, but mine runs like a dream now.
