RPM hesitation

[Cobrajet]

I've experienced that "sticking throttle" before, and I believe it was engine related, not transmission. It did it several times on my way to work, and one time I pulled over, shut the engine off, restarted, and the idle was back to normal. No codes that I can recall, but I think the ECU was trying to compensate for some perceived emissions (O2) readings. I think it went away by itself. I would suspect a dirty MAF, sticking EGR, or O2 sensor before a tranny or muffler. You could always try a 20 minute battery disconnect to reset the computer.

[Joe Isuzu]

thanks for the thoughts cobrajet, seeing as how I just recently did the muffler and transmission work, I feel pretty comfortable that it's related to one of those two (fingers crossed)
and Ldub, thanks for your post as well. Tranny overfill seems to be the culprit here which is a relief to me, very easy to fix and I will fiddle with it over the weekend and get things back to normal
Appreciate everyone's help here!

[Joe Isuzu]

drained some fluid last night, things still aren't the way I remember it before this work (tranny job and muffler) was done, of course, that could be selective memory but it's noticeably better than it was before I drained the excess fluid
happy ending!