bought a 1990 f150 4x4 auto 302 ran ok with blowby replaced motor with a remanufactored long block found out it was out of an older car (mid 80's) everything bolted up properly the only diferance i found was the plugs now with the new motor it will run but wont idel? also had trouble tabing the motor and trans if there not meshed right will they bolt together and will it run???

 

Transmission bolting up shouldn't effect idol of the truck. Check your Idol Air control valve, fuel lines, and fuel pressure. Did you replace the cap, rotor, plugs, and wires?