i got a 94 2500 with a 318 that starts up fine and runs fine untill it warms up to a certain point and at the snap of a finger it starts running real rich and sometimes stalls but starts right back up, i put a new o2 sensor in and reset the ecm but that didnt change anything, i was thinking that may be its the coolant temp sensor or the ecm, do you guys have any ideas?

 

Air filter been replaced of late?

That will do it, if it's dirty it simply 'chokes' the engine and it's no big deal until it warms up.

 

How many miles on it? Maybe time for an injector servicing.