Engine stumbles in '92 Mazda 929


The engine in my '92 Mazda 929 stumbles. It’s especially noticeable at lower rpm’s and on uphill grades with the AC on. But sometimes it happens on the flat with no AC. And sometimes it doesn’t happen at all. I’ve tried fuel injector cleaner additives, which seem to help for a little while but not long term. Suggestions?


How is the rest of the general maintenance? When was the last:

Air filter
Fuel Filter
Plug Wires
Oil and Filter

None of those may be the problem, but let’s get them out of the way. (BTW I believe you did say you had done one of those, but with the new version of the board I was not able to go back and re-read it to figure out what one it was.)

If you changed the plugs (or not) what did they look like? Where they all the same?