Dodge Repair: gear shange wont change, decent gas mileage, dodge caravan

Question
I own a 1995 Dodge Caravan SE with about 115,000 miles on it (runs pretty good, actually).  No one I take my car to seems to be able to figure out why it has a problem shifting from first to second gear.  Some days it runs without a problem, some days it's sticky all day.  I can feel is lagging, like it's trying to go but can't, and I have to floor the gas to get it to shift.  It will then lurch into the next gear.  On a bad day, I have to floor it every few miles on the freeway just to keep it at 60mph.  Some days it's sticky when it first starts up and then runs fine, other days it runs fine and then gets fouled up.  On a really really bad day, when it does lurch into second gear there's a loud thunk, like a knock; the sound is almost hollow, not like grinding metal or parts rubbing together, and I can feel it under my foot behind the gas pedal... It's almost a knock.  I've kept it up on maintenance, except that it hasn't had a tune-up in a long time (every time I got it tuned up it would idle too low and stall out unless I was pushing on the gas, which made it almost impossible to back out).  I took it to AAMCO a few years ago with this problem, which was much worse at that time, so much so that it actually stalled in the middle of a intersection!  It now has a rebuilt transmission, and is better than it was, but no one can seem to diagnose the problem.  And since it only does this every couple of weeks or so, whenever I take it to a mechanic it runs perfectly fine.  They even asked me to come out and test drive it with the mechanic to make sure I wasn't doing anything wrong (not likely) or just imagining it (even less likely).  There's no pattern to the gear stickiness, be it gas, oil, fluids, weather, cold-start or warmed up.  My brother is a mechanic, and he doesn't know what to make of it, either.  Please help!  I love my van, and would like to see it reach 200,000 miles.  Aside from this one problem, it runs quite well and gets decent gas mileage.  Any advice or suggestions would be much appreciated.

Answer
U keep taking it to people that dont really know about trannys   all they will do is sell U a rebuild  and if that does not fix it   oh well hit the road.  Take it to a dealer so some one trained in Chrysler mini vans can take a look and correctly get u back in working order.