91 f150 5.0 strange problem
1991 ford f150 5.0L wont start unless fuel pump primes, most of the time fuel pump just stays running with key in on position. If i turn key on and off a few times the fuel pumps prime and shut off then the truck will start. It will run smooth for a few minutes then the check engine light comes on and has no power and starts idling rough, almost feels like the transmission is slipping but it's not because if check engine light goes off the transmission has plenty of power. When I turn the key on and off until the fuel pumps prime when i first start it the check engine light is off it comes back on after a few minutes of idling. I have changed the fuel pump relay, ecc relay, fuel pressure regulator pvc valve. Any ideas any help would be much appreciated?