[GTP Dad]

The OBDI and OBDII systems are different. The computer will not clear some codes by disconnecting the battery like in the OBDI system. You need a code scanner to clear the code but it sounds like you have an issue that is not going away. As you indicated I would do a compression check just to see what is going on. There is a possibility that you have a dirty injector or possibly a bad ignition module you should be able to tell if anything is going wrong internally by the color of the plugs when you pull them out. A cylinder that is too rich will show a dark wet plug and one that is lean will show a white colored plug. May point you in the right direction.