I successfully installed my longtubes last weekend. While I was in there I put in a new set of plugs, same as my old ones, and replaced the motor mounts. After the install I noticed my car is now idling at about 850rpms when before it just hovered under 1000. My idle also surges now. It will stay steady at around 850 then drop down to about 500 as if its fighting to keep from stalling. When I start it in the morning it has stalled a few times on me. One other thing, I did notice that that my old plugs were showing signs that I was running lean. Do you guys have any ideas of what my problem could be?