So I began having the problem two years ago when I would accelerate from a stop light, first gear just felt extremely weak and it was difficult to get up to speed quickly. Now if I manually shifted into first gear it had no problems 
It then began not wanting to shift from first gear, then when it would shift it would be fine for a few minutes and then it would slam back into first. I finally had enough and pulled the transmission and took it to get rebuilt. So after it was rebuilt I re-installed it into the Jeep, filled it with fluid and ran the engine for about 30 minutes while I checked and re-checked that I had the proper amount of fluids. From there I jumped in the Jeep and took off with no problems, or so I thought. Remember I had the vehicle running for half an hour and everything was warmed up. After I turned it off and it cooled I jumped in to head to the store and sure enough, the damn thing wouldn't shift out of first and then when it did it would slam back down. After fifteen minutes of sitting idling it ran and shifted just fine. Occasionally it would shift weird but nothing crazy. Now I spoke with the transmission shop and I had a full 1-year warranty on the transmission so I called them and took it back in. They toe it apart and said there was nothing that they could find wrong. They re-checked and tore it apart again and put everything back in place again, they replaced all the sensors and everything of that nature and installed a new converter. They fire it up and it still has the same issues The only thing they could find was the speed sensor wasn't always getting power or signal whatever you want to call it. That is where they had to stop because they had replaced everything on the trans side of things and their best guess was it was an electrical issue.
So now the damn thing is back in my garage with a re-built transmission that isn't shifting. I swapped the trans and engine in a few years back and did all the wiring myself, but I had gone years without an issue. So now I am at a loss and I am struggling to find a good starting place to start trying to figure this thing out. Would anybody have an idea of what could be the cause of this? Has anyone dealt with a similar situation? I am up for any suggestions
Thanks in advance.
It then began not wanting to shift from first gear, then when it would shift it would be fine for a few minutes and then it would slam back into first. I finally had enough and pulled the transmission and took it to get rebuilt. So after it was rebuilt I re-installed it into the Jeep, filled it with fluid and ran the engine for about 30 minutes while I checked and re-checked that I had the proper amount of fluids. From there I jumped in the Jeep and took off with no problems, or so I thought. Remember I had the vehicle running for half an hour and everything was warmed up. After I turned it off and it cooled I jumped in to head to the store and sure enough, the damn thing wouldn't shift out of first and then when it did it would slam back down. After fifteen minutes of sitting idling it ran and shifted just fine. Occasionally it would shift weird but nothing crazy. Now I spoke with the transmission shop and I had a full 1-year warranty on the transmission so I called them and took it back in. They toe it apart and said there was nothing that they could find wrong. They re-checked and tore it apart again and put everything back in place again, they replaced all the sensors and everything of that nature and installed a new converter. They fire it up and it still has the same issues The only thing they could find was the speed sensor wasn't always getting power or signal whatever you want to call it. That is where they had to stop because they had replaced everything on the trans side of things and their best guess was it was an electrical issue. So now the damn thing is back in my garage with a re-built transmission that isn't shifting. I swapped the trans and engine in a few years back and did all the wiring myself, but I had gone years without an issue. So now I am at a loss and I am struggling to find a good starting place to start trying to figure this thing out. Would anybody have an idea of what could be the cause of this? Has anyone dealt with a similar situation? I am up for any suggestions
Thanks in advance.
