missfire 75t

[paulin]

Help my 75t touing has an intermitent misfire 2500RPM aprox,if i drive like im 95 years old ie dead gental its ok if i boot it it misses then clears , it developed this problem 2 days after i bought in feb it went back and had its coil packs changed ok for 3 days went back new lamda sensor fitted aweek later back for anew cat ok till last week misfire back but out garentee and engine lights on any clues as towhat it might be.