Hello Everyone
I'm working on a 97 GMC suburban with a 5.7l vortec. it has a P0300 random misfire code that i cannot figure out and is primarily in cylinder #6
what I've done
-Compression is roughly 160
-replaced spark plugs/ wires
-replaced cap and rotor
-replace spider injector with upgraded unit from ac delco
-replaced fuel filter
-pulled distributor to check gear, nothing wrong and check position with scanner afterwards
-pulled valve cover, push rods and valves all move (not measured, but nothing appears broke)
-spraying an brake clean into the intake causes the engine to run smooth and stop misfiring/ misfire goes away at 3000rpms (watching reading on scan tool for misfires)
At this point I'm thinking a hydraulic lifter, or an issue between the spider injector and computer or computer it self