3.7 l. 4WD truck idles very rough . Engine codes says multiple cylinder misfire. We change spark plug and coil and clear codes. Still rund rough and it will stall also after reving. Engine code MIL came on still multiple cylinder misfire.
The spark plugs need to be the cheap copper core plugs and be replaced every 30K miles on that engine. Could be a lot of things. Crank/Cam sensors, fuel system (pump, injectors), false O2 readings...the list goes on. You need a scan tool that can look at real time data to see what's going on with short and long term fuel trims. P0300 only or other codes?
check vacuum hoses for leaks,not connected.listen for hissing sounds.,engine area,all of them!check pcv valve hose,and the valve.pull the pcv valve out,shake it,if it don't rattle,replace it.
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