speedometer? / cutting out and sputtering?

Weird problems lately, 97 cherokee, 4.0, auto, When I go to start it up first time in the morning and drive out of my driveway, the speedometer intantly goes past the 100 mph mark, in fact it is usually buried straight down, Im usually doing about 5 or 10 mph at this point. Then it seems to shift really wierd, and if I try to accelerate it seems like it cuts out, and the rpms go down to about 300. It accelerates very slow and seems like its going to die. It is almost undriveable it cuts out so bad.

But, heres the kicker, it only does the above symptoms for the first mile or two, then it seems like it remembers everything and then shifts when its supposed to and everything, even the speedometer starts working again, (kind of, it likes to flutter around a bit) I thought I might be able to reset the computer so I tried that a few days ago, and that helped for a few days, but its back to doing it again. Im pretty sure a sensor is going bad but not really sure which one. any help?

well, Ive made progress towards the solution to my problem, (no thanks to you guys, lol) j/k. I ran it for trouble codes and apparently the tcm (transmission control module) is bad. Its been getting worse too, died on me twice today.

Im looking on ebay and used ones are pretty cheap, just wondering if one from a 99 would fit on a 97? also does it matter what kind of trans it is. I don't even know what kind of trans Ive got (how do I check?) The ebay listing doesn't list what kind of trans it was either, just that it was from a 99, 4x4, auto.

heres what Im looking at
http://cgi.ebay.com/ebaymotors/Jeep...020QQitemZ300100061331QQrdZ1QQsspagenameZWD1V

I just checked the haynes and fsm, and no mention to the tcm, or any trans computer for that matter? what gives?

does no one know anything about this? am I crazy?

I'd start with the vehicle speed sensor located in the tailshaft of the trans/t-case first.