what spark plugs

I run the NGK's as well. You should always check the resistance of the plugs to make sure they are good. I've had to go back to the parts store 3 times to get a good set of 8 and in the end I just took my multimeter with me to make sure I left with good ones. Spark plugs have 2 joints that can fail and create problems of high resistance so a good one will measure no more than 0.08 Ohms and lower.

You would be amazed at how many actually come out of the box with issues.