Scott Martin
Newbie
Too little information to diagnose over the internet. But always have to check the basics when it happens: spark, fuel and air. Compression is likely not a possibility. You have to "catch it on the act," you know what I mean?
It may be losing fuel or something about spark advancing/retarding, but could also be some vacuum leak that happens intermittently? A scan tool with Live Data is a MUST on these type of problems! Fuel trims is what I would check. Ideally should be < 15%+\- on the long term. If both banks are lean or rich, then likely a fuel delivery problem.
Also check all other sensors and their output values obviously, such as MAF, TPS, MAP, O2s, etc. Good luck.
I do know someone who has the necessary equipment to do all that.