Twice in the last two weeks of daily driving here at 5-25 deg F, my
1999 OB showed the above symptoms. Next morning, normal behavior!The first time, the shifting problem came on gradually -- after 5 minutes or so of driving. I thought for a minute or so that I was running out of gas. The second time, a week later, it came on fully within 30 seconds of starting. It is as if the AT is refusing to up- shift until it finally engages with a "THUNK" and a jolt. Shifts down again with a jolt.
Does not recover during further driving. Overnight cool-down did fix it both times.
Checked fluids. AT oil OK.
The computer code (according to AutoZone) was something about manifold pressure. I had them erase the code the first time. Now, after second episode, it is still in memory, and I can go back and get the exact code if it will help.
The second time was four days ago. Today, behavior is completely normal. Until the shifting symptoms come back and stay, there is not much point in going for service, ("Nothing wrong, $40 please.") But does anyone recognize these symptoms?