PLEASE HELP!!! 97 Mazda B2300. Felt like truck started misfiring, and while driving it kept jerking and the tach needle would fluctuate up and down. Then it would stop and drive smooth again; I thought I had water in tank, so I put a bottle of HEET in the tank and ran great for a couple days. It started again and I spoke with AutoZone employees and everyone said the fuel pump, put a brand new one in, and it still does it. A friend checked coil packs and they were bad; had orange spark, and intermittent. I changed the coil packs and drove it to and from work and on the way in drove great, on the way home it started doing it again. I have no check engine light so I don't have any codes to go on. Any ideas?

 

The 1997 2.3l can run with either coil pack unplugged, so just run on the 4 spark plug on that side of the engine
And you can drive around this way, will just have less power

I would warm up engine first but up to you
Shut off engine
Unplug the 3 wire connector on either coil pack, pull connector back at last 3" from coil pack
Start engine
If you have a steady misfire then ONE or more spark plugs on that coil pack is bad, you can use INSULATED gloves or pliers to remove 1 spark plug wire at a time to see if you can ID which spark plug is not firing
Can also be a spark plug wire issue

Repeat test on 2nd coil pack
Engine should run smooth on either coil pack alone

The dual spark plugs are for extra power, this 2.3l Lima engine ran just fine on 4 spark plugs from 1974 to 1988

Problem with running dual spark plugs like in the Dodge Hemi's, is that you can't tell when one of the spark plugs fails, since the other works
And then if that 2nd spark plug starts to be intermittent....................well only then would you get the misfires


Clean MAF sensor, always, when there is stumbling/bucking

Check/change PCV Valve, this can cause intermittent vacuum leak