1991 560 sel hesitation
 

I am the proud owner of a 91 560 sel with 147k mi but it hesitates from a standing start 80% of the time and looses power intermittantly when around 45mph.. if I am careful and dont step on the gas to hard I can nurse it to speed with no problem but the car begs to be driven fast so thats hard to do.. I think it may be spark plugs and or wires.. timing seems fine any speed above 45mph is flawless.. I simply believe its an ignition issue.. any ideas would e appreciated

Thanks
Demeterial