Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
The first thing to ask yourself is the check engine light remaining on past bulb check?
Just because the TPS and/or the IAC was changed doesn't mean there couldn't still be a problem in the wiring or carbon buildup in the idle air passage.
It may even be a vacuum leak. here is a troubleshooting procedure for the IDLE CONTROL SYSTEM, I suggest you go through it and complete what steps you can.