About a year ago I purchased my first Yota pickup ('93 Auto V6 4WD 170k miles). It's been a great truck. But I'm having 2 problems that I need help with - they might be related to each other, I'm not sure.

#1: Speedometer will drop to zero sometimes when driving and sometimes will go back to correct speed - doesn't seem to be related to any specific reason.

#2: This has happened twice now: After driving about 30-45min. the speedometer drops to zero and then about 5 minutes later the transmission isn't engaged (engine revs up and acts like it's in neutral). Both times I had to pull over, wait a few minutes and then no more problems. Both times I was traveling ~70mph. My tranny fluid is reading high (both when cold and hot). When cold the level is at the hot marks. Could this be the issue?

Thanks