Just completed a roughly 1,000 mile "Great Beer Tour of Texas" with my dad and cousin. My '99 V6 performed admirably, but the one thing I noticed was that when the automatic tranny was downshifting from O/D to 3rd gear at approx 72 mph, it would rev up to where I expected to see it (~3400 rpm) and after a second or two seem to drag back down to just over 3k. When that happened, it wouldn't accelerate and I would actually sometimes lose speed on the hills. It only happened while under cruise control, and seemed to perform fine when I had my foot on the gas. I recently installed an aftermarket transmission cooler and have been checking my fluid religiously; seemed within range to me. Any ideas?

 

trans temp too cool ?

 

Not sure, don't have the scanguage to check it. I doubt it though. If anything it might have been running warm, but again, it's all guesswork at this point.