Always happens after i start it up in the morning, it starts up fine, goes in reverse fine, but when I throw it into drive and give it some gas, the engine vibrates heavily like its got random misfires. Usually happens around 2000 RPMs. If I slam on the gas it evens out and it doesnt happen after that. I just had the whole fuel system done (pump, injectors, filter), its got a new distributor. I also decided to diagnose the car and came up with a code 42 thats not triggering a CEL. Would a knock sensor couse this intermittently?