sgilmer

2003 f150 5.4 Lariat, 273,000 miles. Not sure if these 2 issues are related but I am stumped and have searched/ trouble shot a lot.
I started having only heating issues, cold air at idle and low speeds, I have flushed entire system, flushed/back flushed heater core by itself, replaced water pump, replaced radiator hoses. The issue is a lot better but still does it at times, however since then I am getting mis-fire codes like crazy. It will be a blinking check engine light and then just a constant check engine light. I replaced 2 coils so far, #4 and #1, everything will be fine for a few days and then it will happen again. So I swapped coil packs 1 and 4 with 2 and 3, replaced all spark plugs and thoroughly cleaned MAF. All was good from Christmas Eve until today now it is running rough again and shows these codes at autozone : P0304 #4 had too many misfires in a certain time period. I need help. The plugs and coils did have oil/moisture on them when I took them out to replace. Thanks in advance