I have swapped a 1987 5.0 F-150 engine with a 1992 H.O. 5.0 out of a thunderbird. I have also changed the intake and plenum back to the 1987 5.0 for the air cleaner hook up. I reinstalled the 1987 distributor with the firing order for the H.O. 1992. Changed the computer to the later out of the thunderbird. Now my problem, the motor runs but very,very poorly. It will not idle and has no power. Any sugestions would be greatly appreciated.