Cadillac Repair: jerking, spark plug wires, fuel pressure

Question
91 cadi deville 4.9, just a couple days ago my car started jerking, it occurs every once in awhile when iam driving and only when i start from being stopped, itll jerk a couple times when i step on the gas and then go, it seems to happen more when i try to take off more quickly rather then slowly
So far i have changed the spark plugs, fuel filter, i was think about the fuel pump or my injecters next... but when i think about it, i think it can be my transmission mounts also.
What do u think is the most likely cause of this problem, and were do u think i should start fist.
Thanks

Answer
Hi Alex, This is kind of a tough area to advise because a transmission that is going bad will shudder or jerk on take-off, a bad sparkplug wire or arcing in the dist.cap, weak fuel pressure or mounts could cause this too. What I would reccommend is to open the hood and do a brake torque and see how the engine responds. In other words start the engine and place it in reverse and bring the rpm up to about 1500 for about 5 seconds. If the engine tips noticeably then the mounts to see which ones are bad. If the engine starts to miss then look to the fuel pressure, spark plug wires or cap and rotor. If the engine starts out running ok but the longer it runs the worse the idle seems to get then the injectors need to get tested for shorting. Now do a brake torque in drive and again see what happens. An engine mount can be ok in reverse but appear broken or loose in drive. Get back with me with the results if you need more advise or help. Bill