just got a 91 ponitac bonnevile from my little bro. i ran like crap so i put new plugs, fuel filter,wires and a egr valve in it and it ran good . then i cat cracked in half so i took it out and welded in a pice of pipe. then the muffler went so i got a cherry bomb turbo from meijer what ever was cheap. now the car stalls when its cold. i will go to start it after its been sitting . it will fire then stall then it will fire right back up.then i back out of my driveway andstop and it dies. but once its up to operating temp it runs great and dosnt diei dont think its the exhaust cause it ran with a pen header for a day and didnt die.i think the fuel pump is good i didnt check the pressure put i held the brake and gave it gas and the pump kept a costant pressure no surges or dieing. so im stumped. please help[/align]

 

my knowledge of cats is that they tell the o2 sensor what to do and everyone i know that took it off didn't have an engine very long there rings got fried cuz of the fuel ratios so my guess is the engine is gettig way to much fuel when it finally gets hot it's burning it easier along with your pistons and rings