I have a 1986 f350 that had 6.9 which I changed to a 7.3 idi and a e40d trans. I 've taken the wiring harness, computer and fuse box out off 1995 f350 to run the trans only . When I've installed everything and cranked and put into drive it acts as if its in limp mode, when I put in 1st, or 2nd then it acts normal. Any ideas on problem