Just recently I've noticed that my car is'nt quite feeling as quick as it should be and my worst fears were comfirmed when I took the car out to some roads where i have taken vids before.. :( 95mph where before it hit 105mph.. My first port of call were the plugs where a noticed a bit of oil residue...(very small amount...spilt when oil change was done prob) would this cause such a big difference..and what other bits should I be checking first??