I have a 2004 Isuzu axiom that is that has a check engine light on. The engine is bogging down and burning a lot of oil and is reading a misfire on the number 4 cylinder when I hooked up the diagnostic tester to the OBD II. The positive crank case ventilator was clogged with oil, it helped cleaning the pcv but continued to burn oil and read a misfire on valve 4. When doing a compression test all cylinders are reading 95. To test the coil packs we look at the resistance on the main coil between the plug and power and all had similar resistance on them, the spark plugs had some residue on them but were still getting a spark. When we ran the engine and unplugged each pack the engine slowed with each cylinder was taken offline leading me to assume all the coil packs are doing something. When inspecting the the inside the manifold and cylinders with a boroscope they seemed to have some excess oil residue but otherwise nothing of note. I will be doing another compression test and a leak down test on it, would anybody have any suggestions how to trouble shoot the problem. I am guessing it is some misfire caused by something mechanical but I would not know how to determine what those could be. Most troubleshooting focuses on fuel and ignition but the bogged down engine coupled with the burning oil is difficult to single out.
Any insight would be greatly appreciated.