92 toyota camry over drive
hey,
it just started to do this a couple weeks ago, all of a sudden it shifted from o.d. to drive on the freeway. it kept shifting back and forth on it's own so now i manually have turned of the overdrive and everything is fine, besides the 3000+ r.p.m. if i have to do 60-65mph. every once in a while i'll push the button to engage the o.d. and it will shift up but only for a short period of time. and when it does kick up into o.d. sometimes it stays for a mile or 2 and other times it will kick in and out a couple times before just staying in third. tranny doesn't slip and still shifts good even in and out of o.d.

any suggestions, or a place to start checking?any and all info. will be greatly appreciated.

thank you, Jon

Very likely your Engine Coolant Temperature sensor.