More transmission problems

[Keith1994SSEi]

1994 Bonneville SSEi, new transmission about 3 months ago. Then things started going wrong. First, the car would drive for a mile or so then lose all gears, i.e., the engine would rev but the car woudln't move. First time, the trans rebuilder said it was the PRNDL switch (which was throwing a code).
When that didn't fix it, he said the it was the torque convertor and replaced it under warranty. He also replaced the radiator (not under warranty) and said that the built-in factory trans cooler was leaking and damaged the transmission. OK, so it had over 160,000 miles on the radiator so it probably needed replacement anyway. It has run cooler since then, so I accepted that.
Then the car stopped engaging the transmission when you first started it. You had to let it idle for a couple of minutes before it would go. After that it would go just fine, shifted good, etc., but if it sat for more than an hour it would do it again. But at least once it got going it kept going... The transmission rebuilder determined that there was a vacuum leak. A free fix of what he said was the leak seemed to fix the problem.
Now the first problem has returned.. sorta. Symptoms: When first starting the car, it engages the trans just fine and away you go, shifting normally. Suddenly it will lose transmission engagement, i.e., the engine will rev freely and you won't continue to move forward. After drifting to a halt, if you put the car in park, kill the engine, then restart (I mean you can restart immediately, or wait a few minutes. There doesn't seem to be a cooldown requirement), the trans will re-engage--no slippage--and off you go again. To a repeat performance. I drove the car 5 miles that way last night after my son called me at 11:30 to report he was stalled on the side of the road... The transmission engages fine, then it doesn't. Stop, park, kill, start, go. Works every time.
Oh, yeah--one more thing. If you turn the engine off in neutral and try to restart, it will not start. Won't start in neutral. That's odd. Used to start in neutral.
What can be going on here?

Keith
1994 Bonneville SSEi

[BillBoost37]

On the neutral start, the PRNDL switch is probably not lined up properly.

On the driving fine for a short distance and then working once you restart, this is probably the pump screen getting clogged. Turning off releases the material that has been picked up and allows some fluid to be pumped again.

[wjcollier07]

Interesting. As always, the next best thing to doing anything mechanical is to put in Seafoam TransTune. It'll break down most of the deposits in there that might be clogging things up...but you've got to be sure to change the filter at some point...otherwise that'll become the other fluid restriction. A flush might not be a bad idea in this case either, since the whole clogging at the pump screen could very well be a possibility..and their machines usually flush in both directions IIRC.

[BillBoost37]

Only time I have personally run into the clogged screen it was because of deposits that TransTune couldn't take care of.

[Keith1994SSEi]

Well, I got up this morning and started the car. Put it in gear and it won't engage the transmission at all. Nothing.
Question is, how did I get it home last night and what changed in the meantime?
Keith

[BillBoost37]

May be that you used up the last bit of it coasting into the driveway. Accept the good luck you had as you are about to find out how bad the trans has become.

[Keith1994SSEi]

I guess I will find out. Hauled the car back to the transmission shop today. It's still under warranty, so I hope they don't determine it's something "not covered by warranty."
Sigh.
Keith