Spark plugs and lack of power

[Davidw04]

What are the best plugs for an almost stock Mach. All I have is an intake, off road x pipe and weld in mufflers and an sct tuner. My car feels like it lagging in the mid and upper range. I’m replacing my fuel filter this week and was thinking about going back to the motorcraft plugs from the ngk v-power plugs that I have in it now. Car smells really rich which the fuel smell is normal without cats but I think this is a little excessive to where it burns your eyes and your clothes smell of fuel. And occasional puff of grey smoke on startup. Pretty sure it’s not oil and that it is fuel which could also be an injector. What do you guys think?