I have an -88 Escort 1.6i which in idle is running up and down in rpm with a constant frequency (a couple of seconds between every "up" and "down"). It started with the engine running bad once in a while while driving, and then only for a second or two at a time. It seemed to get too much fuel, but only for a short period. Now it runs bad all the time, but I notice it mostly in idle and in full gas. The fuel consumption is 12 l/100 km, witch is way more than normal (almost double).
I've checked/changed the fuel filter, air filter and distributor cap/rotor, but it didn't help. I've also checked the fuel distributor and the "disk" (I don't know what the part is called in english..) which lifts in the air flow and controls how much fuel is going through the fuel distributor. It also seems to be ok.
Any ideas what the problem could be? I suspect some electrical problem, but I don't know where to start...
/Marcus