I've been having intermittent shifting issues in my 88 MJ. It started a few months ago and it left me stranded an hour from home. That day it started shifting sort of odd. Sometimes when I would take my foot off the gas or break to slow down and then try to accelerate, the RPMs would go up but the transmission wouldn't shift. I could take my foot off the gas and then try again and it would shift. Eventually when I stopped at a red light it wouldn't shift out of 1st gear. I had it towed to a shop and he kept it a week and couldn't find a problem. He said more than likely it just had a valve stuck and it became un-stuck before he test drove it. Now it's starting to do the same type of thing again. It's only intermittent, but sometimes when it downshifts, it doesn't seem to want to upshift when I accelerate and even seems to surge sometimes. I noticed it is worse when it's cold. Could this be a TCU or solenoid issue, or should I start looking for a new transmission? It has 159,000 miles on it.