I Finally got time to upload a video onto youtube of my exhaust sound. I have deleted my resonator and mufflers and replaced them both with straight pipe... On a cold start it is extremely Loud until it warms up and it has a nice sounding idle almost like my brother's '96 Z28 camaro... With the deleted I did notice a tremendous loss in low end torque but that really didnt bother me too much. My only two question are would doing all that cause my car not to have a smooth idle??? Like when its warmed up the rpms go up and down a little like the fans are running but they arent... My second question is would those deletes make it hard for me to go up a bridge? For some reason When I installed my Flowmasters a couple of months ago and till now even when I removed them when I approach an incline Its like the car is chugging and It wont increase speed unless I push the petal almost to the floor. Anyways click the link below to hear the pretty exhaust

YouTube - ‪2002 Monte Carlo SS cold start exhaust‬‏

 

Exhaust sounds great! I personally have flowmaster 40 series and deleted the resonator on my 06. Didnt notice any difference in power there. I can't say I know why this would cause problems as a lot of people do it to their cars, the variation in rpm doesn't seem all that abnormal unless its a crazy swing while idling, as for the loss of torque I would look into other changes you may have made if any, bc like i said not sure why this would cause either of those problems.

 

Sounds liek you might have a MAF sensor going bad, I had one failing in my 97 GP and it had same symptoms you are describing.

 

just unplug your maf sensor while the car is running and if there isnt any change in the idle then its time to replace it