I don't want to start a new thread, but my *stock* '97 is experiencing the same symptoms of late. Usually it does it when it's cold - after an overnight break,for example - but it can go from a smooth idle to a rough one just like that, say, at a stop light. It will stumble early on when cold. It's never EVER done that. The other day while I was having the oil changed, I started the engine and it ran smooth for a couple of minutes and suddenly it acted as if I pulled a spark plug wire off. The engine was warm at this point.
I know I'm due for some plug replacements, and maybe some plug wires since I've never replaced them, but could it be anything else? I've cleaned the MAF, and IAC valve, checked all the vacuum lines, and electrical connections. Whenever I've needed to unplug the battery, it usually gets back to normal within a couple of days.
It could be all a coincidence, but it started doing it a little after I had the transmission rebuilt recently. Hardly noticeable at first, but now very noticeable when it does it. I replaced the oil coolant adapter the other day, but that didn't involve unplugging anything. What connectors, etc, might the transmission mechanics have worked with, or left off, if that's the right rabbit to chase?
...One more thing. I took it to get smogged this past Wednesday and the mechanic, who I've gone to for years, came back with the following, "I've got good news and bad news. Your emissions are good, but it won't allow me to check it now. Did you recently disconnect the battery (which I had) recently" ? The print-out said, "the OBD system was not ready to test" and he told me to bring it back Friday (today) to see if it had gotten back in sync.
Anything here? Thanks again, guys.
"The truth is,everyone is going to hurt you.You just got to find the ones worth suffering for." Bob Marley