Larry, two things come to mind. A possible change in timing associated with a skip of a tooth on the chain/sprocket reup. This will also affect ignition timing b/c the distributor is driven off of the nose of the cam. I don't know if the ECU can compensate for that sort of thing. Also, possible leak between the throttle body and mainfold base. Good luck..

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE