My car has 141K mi. on it and just recently the trans started misbehaving. It began with starting out in 2nd gear instead of 1st on occasion, mostly after warming up, but it's intermittent. It does it probably half the time now. Then I had a couple of instances where starting out in 1st it would slip badly for 5 or 10 seconds and then catch, then it would perform normally. In just the last couple of days it started not upshifting out of 3rd. I could usually get it to shift by stabbing at the gas pedal lightly, but not always. Again, this usually happened once the trans had warmed up. I don't know when the trans fluid was last changed, but it's prbably due. The fluid level is just slightly over the full mark by maybe 1/4" or less and the fluid does not look dirty or smell burnt.

Would a fluid and filter change likely help things? Should the valve body be disassembled and cleaned out? Any other ideas as to what I can do to fix this problem? On occasion it still shifts through the gears normally, and it seems to function just fine then.

Thanks for any help.