96 3.1 SE/3spd auto - won't upshift

I inherited a 96 Grand Am SE with the 3.1 v6 when I got married. This car does not have the original engine. It has the old 3-speed vacuum-shift automatic along with the 3100 V6. I'm guessing it's the engine/atx out of a 95 or something.

When you give the car more than half of the throttle, it slips when it tries to upshift. It's like it gets out of the previous gear just fine, but can't get into the next gear. If you give it around 1/2 throttle or less, it shifts properly. This happens between any two gears. It is very consistent and easy to produce. I am not getting a check engine light.

I've replaced the vacuum modulator, all the vacuum fittings between the plenum and tranny, and built up the seam in the vacuum reservoir with epoxy to help seal it - no go. I thought of the fuel pressure regulator under the plenum, but I haven't had time lately with work to take the plenum off and check that out - we have to drive this car.

Is there any chance it's something outside the transmission causing this? This car is paid for and I want to get another year out of it if possible.

Thanks, guys.

well, with what U describe, I suggest goto www.autozone.com and surf the diagnosis section for your situation. They won't be too much help, as you swapped out of factory-spec, per se, but they might lead you to some ideas.

Tam