stakesd

I have a 99GT and I have replaced my plugs but lately upon start-up it seems as though I have a plug fouling. After a minute or 2 it warms up and smooths out. Could this be an injector, or could it be one of the COP's going out. What a general rule of thumb for replacing injectors, plugs and COP's.
Incidently I pulled the COP and used a multi-meter to test them based on information in the Haynes Manual, although I did not get the same reading as the booked stated (multi-meter may have been set wrong) I did get a consistent reading on all the COP's for Primary and Secondary resistence.

Thanks for any suggestions.