Transmission Troubles!!

[dakthi]

For a while now, my 02 mounty when driving normally shifts really irregularly. From 1st to 2nd it revs like its going to shift, but takes a few seconds before it actually does (its almost like it can't make its mind up what its going to do(LOL)). It does this randomly on a somewhat regular bases all the way till 4th gear. Just had the trans flushed and filled, but it did this long before that.
(Now Im going to be honest my truck ain't stock, Throttle Body, plenum spacer, Cold air intake, exhaust work, programmer, etc)

Recently it has decided to throw another curve at me; the other day I shifted into reverse and nothing, just reved like it was in neutral(I guarantee you I was not in Neutral). after some shifting between gears and a few choice Curse words it finally SLAMMED in Reverse. Then just yesterday it did this again but this time I was driving and hit the brakes hard at a stop light, went to accelerate and NOTHING, just reved when I hit the pedal( lots of honking cars behind me). after multiple shifts to every gear that was possible and around 2 min just to get it to move in any direction; it once again SLAMMED into drive and shifted that way all the way home.
JUST want some opinions on what it could possibly be,( I'm not stupid, transmission to me probably going to crap out soon).
Any advice is much appreciated...THANKS!

 

[JoshMcMadMac]

Start by checking the fluid level, as it sounds like a low fluid condition. It is possible the torque converter is giving up, too.

 

[dakthi]

I checked it this morning and fluid level is good, torque converter was another one of my other quests..THANKS!