186000 miles on truck. 100000 miles had complete tune up and timing change done, now every now and then a misfire is happening, pulled apart intake because thermostat needed change, new coil, plug but noticed that when our remote start was installed back in 2007 they plugged into #5 coil power. Very rarely we use the remote start, could there possibly be a short somewhere? or should we just cut the power wire to the remote start and see if the problem goes away. were not losing fluid and no white smoke upon start up.

 

I would disconnect the remote start and see if there is any change. I would also switch the injector from number 5 to number 3 and see if the misfire follows to number 3.

 

Thank you for the input, swapped out the injector and issues went away, noticed a little black soot mark on original injector. plugs still looked brand new