Ok I have a 91 bko 4x4 5.0l ho e4od i just put a used e4od in it it shifts good and everything is pretty well satisfactory except for when I put it in drive it is in neutral until i slam the shifter as far as I can without going to second gear then it is fine. If you hit a bump it will neutral out. I have adjusted the mpls nothing changed so I bought a new mpls and adjusted it nothing changed. What would the problem be? possible a valve body repair or possible replace?