ford focus 2002 low idle problem varying

That is what it sounds like to me, the pothole shifting something.

things I would check

• look for cracking around the rubber or plastic vacuum lines
• is this an automatic or manual? if it is an automatic and it does that shift to neutral and see if it stops
• was your air conditioning on before? or did it suddenly stop working after running over the pothole? It could be you had a loose wire turning the pump on even if the switch was off but this is unlikely. But this would be a consistent interval and if it was shorted it could bypass the computer which would increase RPM when it runs.
• Do you have a large sound system? if so and you crank the bass this can put a lot of resistance on your alternator.
• check the wires going to your fuel pumps many cars have 2 for fuel injection systems. The pothole could have made a connection work better or jostled a bad brush on the pump motor.

I would check the coil pack connectors and camshaft sensor connector and the vaccuum lines since they are in a relatively close proximity and MAFS Mass Air Flow Sensor my Focus did to and when it became colder weather to but be sure I threw alot of money at it using my ODBII it is for being close not exact at least mine is.