[pods8]

Hi, I've got a 2000 Toyota echo I picked up a couple months ago for a commuter. Its an automatic with ~100k on it. It is exhibiting what I describe as "stumbling" periodically when driving (occurrences are spaced a minute or so apart without any noticeable pattern). Basically seems like its missing sporadically. All the while there is no check engine light coming on which seems odd to me.

With the mindset of air/fuel/spark I've started ticking things off the "what could be wrong" list. I went ahead and cleaned the MAF, swapped in Denso plugs (had some bosch in it when I got it) and put in a set of remanufactured injectors (previous owned said it did something like that before but having the injectors cleaned cleared it up for a while). The problem has gotten better with all these things (prior to the remanufactured injectors I needed to stop driving it for a bit while they were on order because the idle was so ruff it seemed like it was going to stall) but it is definitely still there. The car drives relatively well and is getting 35mpg, but I'd like to get this straightened out especially if it has the potential to do damage in the long run.

Right now I'm not entirely sure what I should be focusing on next, o2 sensor, fuel filter? Could the wiring the the coils be shorting occasionally? The fact this is sporadic has me guessing. Any help would be appreciated.