I have a 1995 Chevy 2500 with the 350 and 4-speed auto for a work truck and recently when startig it up, the tach will not register and the trans is stuck in second. This does not happen every time but on random it will. I have tried a replacment pcm, and that is not helping, in addition to checking the ground wires for the pcm on the engine block. Any suggestions are appreciated very much. Thank You.