I rebuild the 4l30e in my Isuzu Trooper recently. The transmission shifted great and everything seemed ok. Time went on with the trooper as my daily and everything continued well. I passed 1k miles then 5k then 10k. At this point since it had gone this many I was very confident it would last. Every source we talked to stated that if it lasts 5k it should last 100k. Well unfortunately that doesn't seem to be the case.
A few days ago (I'm at about 23k at this point) a noticed going up an incline giving the motor about 45% throttle right in-between 4 + lockup and downshifting that the transmission started slipping. I immediately let my foot off the throttle a to not damage further whatever was slipping. After driving around some more, I found that this wasn't just a one time thing. It was slipping on a consistent basis. I tried starting on a steep incline with it in winter drive mode (3rd Gear) a hammered the throttle and sure enough it slipped quite a bit trying to hold gear. This eliminates it being either the TCC or 4th Clutch, so either its 2nd Clutch or 3rd Clutch. I've never heard of 3rd clutch being a problem so that only leaves one thing.
Anyway, I just am trying to figure out why the clutch pack would start going up all of a sudden. It doesn't slip at all going into gear, the clutch grabs just fine. Its just while trying to hold gear it had problems. As i give it throttle both on flat surface and inclines it begins to jerk/slip out of gear. I can tell due to a loss of power and a noticeable change in engine noise. I don't believe its due to fluid level as there are no leaks. Something else possibly worth noting is that I checked the color of the fluid. It seemed normal in terms of color and smell for this amount of miles/wear.
Any ideas from anyone who knows a bit about this GM tranny?