I've been having intermittent stalls on my 89 F150 302 EFI ever since I bought it 2 years ago. As it turns out, they weren't as intermittent as I thought. In the last few days, I've finally figured out the pattern...

I take a period of normal driving, enough to get everything up to operating temp and cruising speed, etc. Afterwards, I shut the truck down and let it sit for 15-20 minutes. When I come back, the truck starts but it's a little hesitant and I get some unusual exhaust smells. About 3-4 minutes later, it stalls and won't start for 2-3 hours...

My theory is that something is hosed up with the EGR valve or it's position sensor. I'm going to mess around with that some today... Any other ideas?