97 expy 5.4L multiple missfires but only a code for #4

[sirmonkey]

so i'm starting to get a headache from this.. problem started when it got extremely cold here one night a few weeks ago with a random misfire but no codes, as time went on it got worse and finally threw a code for cylinder 4 misfire. given it's a royal pain in the arse to replace 4 i decided to take it to a shop. for them it's showing multiple misfires across different cylinders. trying to see if anyone has had this happen with it only throwing a code for a single cylinder and/or if the misfire on cylinder 4 could be causing the others to missfire?

 

[docraymund]

Do a cylinder balance test first on all cylinders as a baseline then go from there.