For the past month or so, I've been having troubles with my 1995 Silhouette L27 3.8/4T60-E.

The trans is slipping during 1-2 upshift.

Down shifts harshly when coming to a stop like the lock up converter isn't unlocking.

And once in awhile at take off, it will act like it'* stuck in 3rd gear until I manually downshift into another gear.

This is very intermittent and will do it whether it'* hot or cold.

Now, if I leave it in drive instead of overdrive, I get none of that static. No slipping, no harsh downshift, no third gear starts.

I put a trans cooler on when I got the van because they produce so much heat that they will kill the trans is pretty short order. I've ohmed the solenoids and they check out. Using TunerPro, I have no stored codes in the computer. The trans runs at about 180 degrees tops under any conditions.

Not long ago, the idiots at Jiffy Goob talked my wife into a trans flush and I'm wondering if that hadn't caused some problems.

Bad solenoid?

If you had a bad solenoid, putting the selector in the D position from the OD position should not make it operate any better.

You may want to look at your transmission range sensor (AKA neutral safety switch) as it tells the computer what gear it is in and is your shifter linkage tight or loose?

I have a couple of switches...I'll give that a try, thanks!

Let me know how it works out. That was just an educated guess.

That wasn't it.

Anyone else have any ideas?

There is very little that you can do externally to these transmissions and at this point, based on what you have said and done and without actually driving the vehicle myself, I'd say that you probably have an internal problem.