99 grand prix stalling at different rpms

[santi]

Ive got a 1999 grandprix gt 3800 series 2 its got a loud squacking noise under the hood .The water pump was changed and the belt pully and that did not solve the problem .Then all of a sudden it wants to stall then the rpm jumps and then runs fine then starts again trying to stall even at high rpm while driving.I took to a mechanic and it ran fine but had a code for a power spike they might be unrelated the sound and the power spike.The alternater when running normal temp is frying hot to the human touch.The car has over 100 k on it.They cant find where the sound is coming from because its inter.The mech said that a power spike will make computer reset or shutdown.Im not sure of this so i might just swap the alternater and see if that helps i hope.Anybody else have this problem

[BNaylor]

What was the DTC code? Basics either fuel or ignition. Ignition - spark plugs, wires, coil packs, ignition control module (ICM). Another possibility due to the stalling is a crank position sensor. For fuel check fuel pressure at the front rail to make sure it is in specs.

Check the voltage at the battery across the terminals with a DMM and check the alternator output before arbitrarily replacing.

[santi]

Thanks for the response It only does it at operating temp the moniter display blinks low when theres lots of gas.when i drive it in the morning its fine until i park it shut it off then wait 5 minutes go to start it and it idles then revs and then tries to stall then it idles fine then revs and tries to stall .

[santi]

proplem solved ...mass airflow sensor and a gromet missing from the pcv . Thanks for the help.