93 Deville loading up!

My sons 93 deville 4.9 v-8 new catylatic converter,new plugs, new plug wires,new rotor, new cap, new exhaust manifold pipe back. seems like when it is cold runs rough and loads up then most of the time it runs fine with tire smoking power last night my son said it had muffler prob. I get there no crap it looked like a a baby was inside the muffler and kicked it completely open it was brand new muffler not no more any help would be appreciated

Check for codes in the obd system, many things can cause this, (loading up?), look for coolant temp inputs for starters.

Thank you for the info I will let you know!!!!

Crewdawg692
A-10 Crewchief


Check for codes in the obd system, many things can cause this, (loading up?), look for coolant temp inputs for starters.