The codes you retrieved from your computer are ABS codes and have nothing to do with your engine. The definition of these codes are as follows:
26 Right Front Excessive Wheel Speed Variation
27 Left Rear Excessive Wheel Speed Variation
28 Right Rear Excessive Wheel Speed Variation
As for your misfire, because your engine idles excessively high, you probably have a vacuum leak either in a hose/line or an intake manifold gasket.
This will give you a "Lean Misfire". This means your engine is ingesting too much air and the computer can't compensate for it by adding enough fuel. This will also blow your motor eventually.
You can also test your ignition system to eliminate that as a potential cause.
With your engine idling, pull the spark plug wire on each cylinder one at a time. If the engine stumbles and/or the R.P.M.S drop significantly, then you'll know that cylinder was firing correctly. If there's no change, then that cylinder was dead. (When/if you come across a dead cylinder, make sure the injector for that cylinder was firing by listening to the injector with an automotive stethoscope. You should hear a steady "clicking" as the engine runs.)
If you find a dead cylinder, then you must track the problem down by tracing the system from that plug back to the coils.
Sunday, April 25th, 2010 AT 9:12 PM