its only when the car is in OD and the rpms are ~2000. unfortunatly this is where the car is usually at. Ive gotten it from 60-80, its not dependent on the mph, its more related to the rpm. I thought it would be the TPS but it never happens in other gears.

I am not going to rule out the TPS, i would rather replace a $70 sensor than get a new tranny, but I dont want to get both either. Where would I get scanner to rule out one or the other? I usually only use the cruise at 60+ mph.

An auto parts store will scan for codes for free, but you need to drive it while you're tapped into the data stream to see what the trans/tps are doing. It'll even tell you what the cruise is doing. You'll need to buy, borrow, or steal a scanner, or get your mechanic who suspects the tranny to go along with his scanner......to back up his suspicions.

Do you live near any other member that may have a scantool?

DrJay here to show love. Two things I would narrow it down to. ONE: If the cruise control doesn't stay engaged, or drops out of cruise, the brake switch can usually be adjusted. But since its only OD that your seeing it that narrows it down to: 4T60E transmissions may drop out of drive while cruising; shift erratically; or have no second, third, or fourth gear because of a bad ground connection for the shift solenoids. So your mechanic was right, the solenoid is probably the culprit but fixing a ground I'm sure is cheaper than replacing it. Take that info to your mechanic and see what he says.

we have a local shop that specializes in trannys. I will probably take it there and get their opinio, I probaby need a flush anyway (its getting a little rough).