I have been dealing with an issue on my 2004 Jeep Grand Cherokee since last October. It has a 42RE transmission. At this point I'm not sure if it is electrical or mechanical. It functions fine except it has absolutely no acceleration (reverse works fine). I have replaced the transmission solenoids multiple times, the entire valve body, checked and replaced fluid multiple times, checked wire connections all the way to the transmission, and a few other things like messing with the TV cable and the linkage. I also thought it could be the PCM and replaced that as well. For what ever reason, it still doesn't work. I will add that I got it to work for about a week in January. It drove great with very few issues. Then as soon as I disconnected and reconnected the battery to remove some codes, it stopped working again. I'm running out of ideas and I find it hard to believe its mechanical, but I'm not sure. Any insight would help so much.

I also have a new symptom and a little bit more data. I found out that it does not have no power. It's just very week. When jacked up letting the hind wheels spin I can accelerate and shift through all the gears freely. However, neutral also has power. When it neutral it appears to be stuck in second gear. Could this maybe be a frozen clutch pack or something along those lines. Specifically I tested neutrals rpms to mph while raised. It was 8 mph at 1000 rpms, 20 mph at 1500 rpms, 26 mph at 2000 rpms, and 33 mph at 2500 rpms. From what I could tell this was second gear.