check engine light / tune up items
I was on this forum previously and always enjoy the flow of information.
My CEL came on after a few days of pinging /rough idle at lower speeds. The code was read at auto zone and they said cylinder 1 & 4 are misfiring. Plugs are 15K miles old and wires 3 years. Coil pack is less than 3 yrs old as well. I changed wires last night and saw no difference. I also switched out air filter. Additionally, I took air filter case out and sprayed the inside of the MAF heavily. I put the red tube that comes with can in the bottom opening of the MAF and in the side opening. I did not unscrew MAF and clean it that way. I had neg battery cable off for about 15 minutes. I hooked back up and heard 1-2 possible misfires, then ran fine and no hesitation while accelerating from 1k RM ( low idle speeds).
Is it possible MAF was dirty and 1-2 misfires were flushing out the cleaner? I also used throttle body cleaner and a gas additive.
If CEL comes back on, what should be my next step?
Also, what are the things a tune up for a 178k 2001 ranger 2.3 liter should have done. I have changed the following:
fuel filter (this weekend)
rear axle differential
Should I be concerned with O2 sensors and PCV valves?
Thanks in advance