1999 Ford F150 Misfire

Have a 1999 Ford F150 with a F250 motor in it. It is having severe misfire issues almost to the point where it will just barely keep up to idle. I already replaced cylinder 4 & 5 coil packs and still have the same run ability issue.

I have not tripped a CEL yet, but it runs poorly and I am afraid as bad as it runs it is doing harm to the cylinders. Any advice on what to check, here? It just runs absolutely horrible.

Thanks for any help or advice offered… 😉