I'm at my wit's end, help!

I have a 1991 Jeep Cherokee, 4.0 automatic. I went off roading where I took on water. Engine didn't stall and I made it out OK. Engine ran rough for about 5 minutes and cleared up. The 20 minutes drive home was OK and so was the 20mile drive a week later. About a day later I started it up and it idled at 1500-2000 RPMs when normal is around 700-800 RPMs. After a couple of minutes it returns to normal RPM. One time it almost died while idleing for about 5 minutes and got a code "MAP Signal Fault."
I drove the jeep for the first time with the high idle and had to hit passing gear to stay ahead of the traffic. When I got into town in 30 mph zone, it didn't want to shift from 1st. Now, all of the time, I have to get the RPMs up to 3000-3200 RPMs and take my foot all the way off the accelerator for it to shift from 1-2 and 2-3 or let it get all the way up to 4000-4500 RPM and it will shift on it's own. Fluid level is OK and not discolored. Disconnected kick-down cable and still the same. I haven't go a clue abot this and don't want to tear anything apart if it is just a sensor or something simple. Any advice would be greatly appreciated. If I can get the help to fix my problem, I would definitely make a donation since it would save me taking it to a shop. I have always fixed my own vehicles.