I just bought a 89 f-150. The engine was replaced with a 5.0. It is very slow to get speed and only max at approx 45 mph. Idles rough then dies every now and then.
I just pulled the eec to see if they put the one for the 5.0 in. How can I check to make sure it is the right one? any other help?
89 f-150 xlt lairiat,4X4, auto

 

Was the swap just done, or did it run ok for a little while after the swap?

-Jon

 

I bought the truck that way. Don't know when it was done

 

is there a way to know if the prevous owner changed the eec and tha wiring harnes? I do know that the 351 exhaust manifolds were used because after taking the right one off because of a leak, the mounting holes were drilled out and the 302 gasket did not line up properly. Just bought it 2 days ago have not been able to drive it. Body and frame almost good as new.

 

A 351 manifold should bolt up to a 302 without making any modificiations. So sayign that the holes were drilled out and stuff doesnt align seems interesting.

 

Swapping ECU's won't make a difference.

Check the firing order... the 5.0 non HO should be 1-5-4-2-6-3-7-8

Next I'd look for trouble codes. Check the TPS (this caused lots of idle probelms for me) and the EGR too.

You could also have a vac leak too.

Hope that gives you some options where to start looking.