i have owned 3 other mustangs... i recently picked up my v6 2002 with 127k miles... after a cold air intake, a used
flowmaster 40, plugs, fuel filter... i then ran a can of seafoam thru the tank.... a week or so later, i put 2/3 of a can down the throttle body via the brake booster line... then rest in tank..
let sit for 15 min..then crank and rev between 2000-3000 rpms (not too high).... til most of the smoke clears.. then take for a spirited ride.... i think you will like the way your throttle response improves and your engine smooths out .... the seafoam will burn some of the carbon build up out of the motor that has built up over the years.....that engine should last as long as you want with normal driving...let the motor breathe... service the car and seafoam ... you should see a big improvement..