My VX SS had a constant misfire and dead spots after 3500rpm. I changed the plugs, leads, coils, injectors and O2 sensors trying to rectify the problem. Nothing changed till I did the injectors. The car started up Brum then idles like it wants to stall for about 30 secs then idles normal. Also since changin the injectors, I can’t rev past 3500rpm. Massive dead spot. I was told it’s a vacuum issue. Where do I go from here? Everything was bought from mace. STD coils and injectors. I want to fix the misfire amd deadspot before getting it dyno tuned. Or does the dyno tuning fix this issue?