sputtering/loppy idle

[302fordracer]

well occasionally my car while driving down the freeway will jolt or sputter and today while idling at a stoplight the idle fell a few hundred r's and bounced between 300 and 500 rpms for just a sec and then started idling fine again...any ideas...recent tune including timing check new plugs, wires, cap, rotor, and fuel filter. Plus I use 76 gas 92 octane every time...oh and I park outside and have been usuing a water eliminator MOST tanks but not on this current tank plus a few tanks in the recent past I havent used it I can't remember but I'm not sure I had this problem while using the water eliminator so that could be it but what other ideas you guys have? fuel pump? something controlling the pump such as a wire short??

 

[HISSIN50]

i would start by pulling codes to see if something is stored (even if the CEL is not illumintated, a code can be stored in the KAM).

gotta narrow down whether it is fuel or spark related (spark seems more likely to me, but that is purely conjecture).

good luck.

 

[302fordracer]

you talking about the key on key off thing? if so how do you perform this check and how do I figure out what me readings mean?

 

[HISSIN50]

yep, that KOEO and KOER are two of the tests. i think your FAQ has a run down on doing it. if not, do an internet search (most of my stuff is two digit fox stuff).
in some parts of the country, parts stores will pull codes for free.
good luck.