I've got a '94 with a 3.0 six cylinder, five speed and 140,000 miles.

Driving home yesterday, engine warm, 75 degrees outside, it starts missing and hesitating. Smooths out on its own and I continue into town. Stop off at the store, get back in, won't start. Crank and crank and crank...finally starts. Continue driving, hesitates momentarily again, then smooths out on its own and drives fine. Park it, try starting it later, no bueno. Crank and crank and crank. Just about when I'm ready to give up it finally catches and starts. Runs fine all the way to the mechanic. Long story short, mechanic can't find anything wrong. Thinks it might be MAF but can't say for sure.

Any thoughts?