no idea WTF this is...

i've been having some chronic electrical problems with my '97, mostly related to speedometer function. have had the ECM replaced, and a couple of sensors. anyway, i'm driving home this afternoon, the check engine light comes on, and a minute later, the car acts like i just put the shifter into neutral... press the gas, engine revs, but no "go". i pull over on the shoulder, shut the pig off, let it sit about 10 seconds, restart it, and everything is okay again, except the check engine light is still on. this was the second time this happened, exactly the same way. after the first occurrence, i took it in, but apparently there were no stored codes, so the guy at the shop couldn't tell me what the check engine light came on for. i don't think this is a transmission problem, otherwise it wouldn't return to normal after i shut it off and re-start it... anyone got any ideas what the heck this could be? are ZJs of this vintage prone to chronic electrical problems, or did i just get a crappy one? my '93 never gave me any trouble at all...