1994 xj12 marelli ignition maping jumper

Can someone tell me if my car is supposed to have a "jumper"(yellow
coiled wire) coming out of my relay switch. Its located on the drivers side of the engine bay in between the coolant resevior and where the hood latches in place. There is a grey switch there. The reason I ask is because i just took my car in for a tune up in new york city and it came back running lousy.I read on another site that marelli v12 have this so called jumper that retards the timing when removed.I don`t see the jumper on my car and if was supposed to have one I believe the repair shop might have removed it and kept it.Can someone with an 1994 xj12 look for their relay
and let me know if they have the yellow jumper wire.Ill try to post the link where I read about it. I am somewhat freaked out if they removed it
because my car was running and idling so smooth you could not tell if the car was on or off .now the car vibrates somewhat at idle. The other thing it could be is that they ragged the hell out of it while they had it.The only other thing it could be is a faulty spark plug. What i would like to deduct from my reasoning is the mapping jumper so... any response on that would be of up most importance . thank you.also if you live in new york I suggest you DO NOT take your car to ALL SPORTS AND CLASSIC COACH LTD. they are on 512 east 74th street in new york .They suck and honestly whether or not they took my jumper they really suck.They charged me 1200.00 to replace my spark plugs my fuel filter and I think that was all they did. My car is driving worse then when I brought it to them and they might have taken my mapping jumper, Needless to say i am very upset sorry for the rant.