I have a 99 jeep grand cherokee ltd, 4.0 L, 6cyl, auto, 4wd, 87000 miles. My problem is that on the first start of the day and when the engine is cold, the transmission wont shift from 2nd to 3rd until engine revs to about 4500 rpm. After first 5 minutes of driving, everything back to normal. No other tranny problems thus far. Any solutions or suggestions?

I had the same problem with mine. Since the transmission is aluminum it has to warm up. My solution was a new trans, which was replaced under warranty.

I have a 99 grande cherokee , it revs to about 1500 rpm on start up which is normal but know going down the hwy it will go from 2000 rpm to 3000 rpm which is scary! what could be causing this!

I'd begin by having the trans fluid changed and making sure there isn't an excessive amount of debris in the pan (there is always some but should not be obviously a lot) You may have a slight varnish buildup inside that becomes less sticky as the internal temp rises.