Transfer Dump problems with remote backup using starter to back truck up to trailer

I have an 03 t800 transfer dump truck. to hook up to trailer we (transfers) put it in reverse with the key off and press a button at the back of the truck that engages the starter and backs the truck into the draw bar thus locking the pintle hook. the problem is that it acts like I have a low battery and won't back up. I have replaced the batteries, battery cables starter relay and 135 amp breaker and the starter and still it acts like low batteries. It will almost always start right up with the ignition switch (in cab) but if I put it in gear rrrh and no movement. I am wondering if the motor it self is somehow the problem ?. I've heard of injectors dribbling causing it to hydraulic, but this happens seconds after shutting the motor off with the trans in reverse and attempting to back it up with the remote starter engagement button.Then I can jump in the cab and it will start righ up I've also tried the cab ignition switch with it in reverse and it does the same thing rrrh and no movement. And no the park brake is not on. any body have any ideas, it would be greatly appreciated. Again everything is new less than 2 weeks, batteries, cables, starter relay (in battery box) 135 amp breaker and the starter replaced today 04/08/14. The reason I replaced the starter last is I just replaced it a few months ago and that didn't change anything. when the ignition is shut off the remote starter works independently of the computer as far as I know it is as isolated circuit and I have replaced everything in it. Frustrated.