2002 ford focus zx3 bucking and bogging down

[Lovelyvanity]

What causes random bucking? Changed the plugs gapped them to .050 myself but no change? Bogging down is no longer a issue cylinders 1&4 were missing cause bad plugs but that's fixed now.

[Sponsor]

[whynotthinkwhynot]

It could be adjusting to new fueling conditions- it was running lean before because 2 cylinders weren't firing. It could also be some other issue like a leaking vacuum line, or stuck EGR. You can do an MAF cleaning and an A/F reset to see if that will clear it up. Simple stuff: Remove MAF, clean with spray MAF cleaner. Shake, allow to dry. Install. Disconnect negative battery terminal for 10 mins. Reconnect, start engine, do not touch accelerator. The idle should settle around 1k rpm, and fluctuate slightly. Time it- 5 mins of idling, and then the idle should drop, it might take 6 mins. Now the A/F is reset, and you will re-map, which might mean reduced fuel economy for about a couple of weeks.