Howdy folks, Reborn here again with another question about my 86 Trans Am. This time regarding my TH350.

The transmission is fresh rebuilt back in July or so of last year, with 3783 miles on it. Recently it's been kicking down from third to second then immediately jumping back into third gear. Today as I was accerating onto the highway in second gear, it dragged back like it was trying to drop into first gear three times before I hit my shift point and went into third. Here's the kicker: the Kickdown cable is NOT hooked up on this transmission. My uncle, who has rebuilt these for many years for our local (Pennsylvania) drag racers went over all of the hard parts and made sure everything was in good shape. It was rebuilt with a good TransStar Master Kit, which is what he's used a thousand times with no issues. He also rebuilt the valve body and used a NoYoYo shift kit (another part he always uses and trusts), plus blocked a fluid passage to build more pressure (which he also always does). We used a stock OEM converter that came out of an 81 Camaro, the unit was known good and checked over anyway before we used it. It ran great for a little while, even barking the tires during the two-three shift. Now the shifting is getting softer and I have this unexplained downshifting issue that seems to be getting worse. We also have a mild fluid leak that we can't locate. I do keep it topped up on fluid however.

Just in case you ask, it's mated to a very mild 305 build pushing 9.5:1 compression, with true dual 2.25" exhaust. The rear end is the stock 2.73 rear geared open diff, and as far as I know it's never been touched

Thanks in advance for all the help folks, hopefully you all can give me the advice I need to figure this one out!