92 bonny codes 21 & 34

HI, I need help with this engine which was removed and repaired (new crank and bearings). After replacing engine car ran fine for 30 min. then stalled. after determining that codes 21 and 34 were stored via paper clip, we used alldata to find and run diagnostics for the tps and maf. We had spare parts from a junkyard and tried those also. same results. the car starts and quits after 8-10 seconds. intermittently it will run fine for 30 minutes as at first. We haven't eliminated some wiring harness problem, but have tried wiggling with a scan tool attached. Could this be a PCM problem and what is involved in replacing it? Thanks for any suggestions.

Welcome to AF. Got good fuel pressure? Don't just go by the codes. The tps would not normally cause this, the the maf could, check all the connections, if the maf is in the duct make sure no cracks in the duct to the throttle body. Get a scanner on it and look at the tps and maf inputs to be sure.

Thanks Maxwedge,
I'll check pressure tomorrow. We did use an Actron scan tool borrowed and the inputs check out. When I find out more info I'll post for more feedback. Keep in mind that my son is driving my 2001 F150 until this car is fixed!