I finally bothered to get under my car and find out what kind of transmission I have, and found a GM TH 700R-4. From what I've read (which isn't much), it seems to be a good transmission, but it has always seemed to be the weak point of my car. If I accelerate too fast it slips, and when it is in drive (and only drive), there's a weird vibration that I can feel through the petal (vibrates for about 1/4 second, pauses, and then vibrates again, in a cycle, faster at higher mph).

I don't have the funds to buy a new tranny, or even rebuild mine, and I'm not very skilled in mechanics. I've been thinking about conning a friend into helping me do a transaxle overhaul, but I don't know if that will help.

I saw a couple shift improving kits, but I don't know how much of a gain it will have, and whether or not it'll shift evenly or quickly shift through the lower gears and get to overdrive at 35mph.

 

What about this...?

http://store.summitracing.com/produc...earchtype=ecat

 

You might want to check to make sure that your TV (throttle valve) cable is still connected from the carb to the transmission. (disconnected or broken cable) Sounds like you are not getting enough line presure as you advance the throttle to keep the clutches engaged. Just verify that it is connected and that there is return spring presure on the cable. Either that, or the the clutches are toasted and can't hold.