I've been noticing over the past month, on a few rare occasions, my 850 (base) has sputtered while driving on the freeway. They are around 1 or 2 second sputters, almost like a couple of 'bucks'. The sputter has occurred at lower speeds around town once or twice upon acceleration, but I've primarily felt it on the freeway over 55MPH while going uphill. My first guess was bad gas or water in the tank. I refilled and the problem went away for 2 or 3 weeks but has now returned.

What I know: hard acceleration does not seem to be affected (although I haven't put it to the floor), engine has been warm each time from medium or long-range trips, no dash lights or CEL, nothing.

Thanks in advance,
--
David
1995 854 Sedan, Naturally Aspirated, 166k mi
No mods but open to suggestions.