Misfire and cruise are likely not related. Cruise most often goes out when the amplifier goes bad. If I recall correctly the amplifier module is behind the glove box, and I just swap in a junkyard one whenever one fails.
For the misfire, try to find out if a specific cylinder is missing. At idle, disconnect the spark wires one by one and see which one makes no difference. Check for codes indicating a misfire on a certain cylinder. You can also run a cylinder balance test after the KOER test to get it to tell you which cylinder is not contributing. Check spark plugs, if one looks different from the others that is a clue.
If you can isolate a specific cylinder that will make diagnosis a lot easier. Check for spark physically, by removing the spark plug, connecting the plug wire and grounding the base of the plug while cranking the engine over (remove the fuel pump relay first). You should see a strong spark. Check compression in the cylinder. Check for the presence of fuel; if the plug is not wet with it, check that the injector is being pulsed using an analog multimeter or noid light.
Hopefully you can find a specific cylinder that is not firing. If it seems to be a general misfire on random cylinders, check for anything that isn't working consistently. A crank position sensor that is damaged, worn out or too far from the pickup can generate a weak signal. A dirty MAF sensor can throw off the fuel mixture enough to cause poor running. Vacuum leaks can cause a lean condition, which the computer may try to compensate for with excess fuel.
