What does it do from a dead stop if you shift it into the 1-2 position (first gear) and floor it. Does it have any power then. If you have not tried that, then try it. If the torque converter is gone or going, it should be obvious running this test. The power response should be obvious. If the engine revs to 3000 rpm and the Jeep just crawls then it is a transmission problem, if the jeep takes off with power, then your problem may be the TPS sensor like mine was. Mine had power in first (1-2 position), but in drive it kept shifting up to the next gear at like 1800 rpm even at WOT so it never showed any real power (which is at 2500 to 4000 rpm apx) and then it wimped out at like 60 mph even at WOT which was also a TPS problem.
Once again the torque converter only works if the transmission fluid hydraulic pump is working right, and if the valve body valves are moving into the right positions to get the fluid to the torque converter.
I assume you have checked the transmission fluid level? If it is low, the torque converter will not work properly, no power.
You might try draining it and then make sure you put in the right tranny fluid for that year model. Sometimes the shops put the wrong fluid in these transmissions, and the tannys don't like it. There are several posts here by 5-90 on the proper fluid for these trannys. Also, if you are absolutely convinced it is the transmision, you might try a can of transmission additive like Trans-X as a flush first to free up any stuck valves in the valve body, before draining and refilling the transmission. You drain some fluid (up to a quart), add the quart of trans X, drive it for 10 to 20 minutes, then drain the transmission and change the fluid and filter.
Beyond that I would try and find a reliable shop that is willing to hook up some gauges and maybe dyno test it and pressure test the pump, etc. to see if is the transmision, and the better equiped shops should be able to verify if it is the transmission and if so which part is definately bad. If it is the pump or valve body, they will not be able to verify the torque converter, but you will know where to start.
Forget the IAC, It has nothing whatsoever to do with your power problem.