I have a 93 ford f150, the truck has been sitting for 3 years it needed a motor so I put one in it, the transmission was shifting fine when the guy sat the vehicle up. i changed fluid and filter it shifted fine for about 3-4 days then it stopped shifting in 3rd gear I can put it in d2 or d1 and put it back in D. It will shift with no problems. So is my trans on its way out? In need of some help please.