OK so here is how it goes, 2 weeks and some change ago I put Mac L/Ts on and completed the install, now during the install I have replaced the spark plugs. Now I have noticed that after wards I had the check engine light on but didnt really notice anything was going wrong until last friday, up to today, here is what she's doing, I start it and everything is fine "except for yesterday it reved to 1500 rpm and stayed for a min or so and then dropped", but after it is started and is on for a min or 2 it starts to lope a little. Now I am off to drive it, there is a popping sound on the passenger side, and it feels like it is running like a V7 so I pop the hood and check around and find the #3 spark plug is loose so I check it and tighten it down. I still have the same problem, so i put one of the old spark plugs in and ... yes still have the same thing going on. I have noticed a small leak coming from the EGR tube by the headers but do think it would do all of this. I am pretty lost here, any suggestions would be a help, sorry for the long post.