When I start my car is runs like **** at first. If i dont keep my foot on the gas the engine will stall. Although once the car gets warm it usually runs great. Except ive noticed my idle will sometime be steady at around 800rpm and for whatever reason sometimes it will be around 500 or a tad lower. Ive already cleaned the hell out of the throttle body, which helped a little. I also replaced the injectors and installed new pushrods and lifters and new head gasket.

 

Perform a test on your 02 sensor,or check for a vacuum leak,I'm having the same issue with mine.

 

Any codes triggered?
If the lifters have the proper preload, TPS voltage is in spec & the IAC has been clean and reset accordingly to the multiple steps outlined in the Factory Service Manual (FSM)....check the timing sounds like it may need a little more advance.

 

The Coolant Temp Sensor is it's choke - Colder, more fuel; hotter less. You need to verify that it agrees with ambient after it's sat overnight. Hookup a scanner so that you can see what the ECM is seeing or spend 12 Bucks on a new one and just plug it into the harness. If it starts up and runs right, replace it.