problems starting

My 1993 Cherokee usually starts fine in the beginning, but if the temperature doesn't get high enough , it is almost impossible to start back up. Sometimes if I wiggle the gearshift and fuss at it enough, it will start. If that doesn't work, I have to wait until the engine is cold again before it will start again. Does anyone have any suggestions on what the problem could be?

Had the same problem last year, playing with the gearshift to get it to crank. Problem was neutral safty switch. Switch is expensive to replace, had rebuilt myown after reading up this page:
http://jeepin.com/features/nss/index.asp
Hardest part of the job is getting the switch itself off, as the page says "thread the retainer nut a few turns" this will be the best way to pry it off.