jumping idle when releasing gas pedal

previously, I had a P1404 code, I used carb cleaner to clean the EGR valve and this code has not shown again until now. I still has other two problems with my car. First, sometimes I cannot start the engine with one ignition. When this happened I wait several second and start again. Usually ,the second ignition make engine crank and hard to start. And this problem does not happen if I park the car for very long time(overnight).
Secnond problem: during acceleration, when I release the gas pedal, the engine speed will suddendly drop to very low and then back to normal idle speed, and this does not happen every time.

Please post the year and model Grand Prix to include engine size and mileage. TIA.

its a 01 gp gt 3.8l non-supercharge mileage 13k

I assume it's just a GT not a GTP, as the only engine option for the GTP is the supercharged Vin-1 3800.

Note: Just so no one gets lost, the OP mistakenly stated it was a GTP with non-supercharged engine in post #3, then edited and corrected his post to GT after I posted the above comment.

I assume it's just a GT not a GTP, as the only engine option for the GTP is the supercharged Vin-1 3800.
thank you, i've changed it.
And I also made some changes in my first post. There is a discrepancy in my description. Actually, the engine will be crank in the second ignition

Try unplugging the MAF (Mass Air Flow) sensor. This will cause the CEL to come on due to it being unplugged, but if the idle stabilizes and the car runs better with the MAF unplugged, then the MAF is your problem.

during acceleration, when I release the gas pedal, the engine speed will suddendly drop to very low and then back to normal idle speed, and this does not happen every time.

I think I would have the IAC motor off and look over the port. Sounds like the IAC is unable to compensate fast enough (or the port is restricted by carbon or gum) when the throttle blade goes back on the closed stop (IOW when you let off the gas).

FWIW, the IAC (idle air control) is a special metered "air leak" around the main throttle blade which is modulated by the PCM to control the idle speed to a target value.

Eventually ETC (electronic throttle control...street name: "drive by wire") combined the two features as the ETC motor can also modulate the big blade finely enough and quickly enough to control idle.

Try unplugging the MAF (Mass Air Flow) sensor. This will cause the CEL to come on due to it being unplugged, but if the idle stabilizes and the car runs better with the MAF unplugged, then the MAF is your problem.
I change a new MAF sensor last year, I hope it is not dead again