94 Grand Cherokee won't start

I have a 94 Jeep Grand Cherokee 8 cylinder that has caused me nothing but problems. To make an incredibly long story short, my car won’t start. Sometimes. It was running fine a few months ago until one day I went to go to work and it wouldn’t start. It would turn over but wouldn’t start. 3 days later it would fire up again like nothing happened. The next day it would barely start. I’ve had this thing in the shop 4 or 5 times and my mechanic has no idea what the problem is. Every time I take it to him it starts fine. We’ve tried an alternator, we tried a new catalytic converter that had been falling apart, a new fuel pump which wasn’t putting out enough pressure. I’m at a loss. I’ve wasted way too much money at this guessing game, I don’t have enough money for a new car. I need any help I can get.

How about plugs and wires? Did your mechanic try that yet? I’m certainly not an expert - just an idea.