My 90 XJS V12 has little torque off the line and sometimes, but not always, under load it changes sound like it's lugging. If I back off it smooths right out. Over 3K it sounds smooth and seems to have power. I still have basic maintenance to preform like cleaning air filters and changing plugs so that could be part of it but all the posts for TPS's have me wondering. Anything elde I should be looking for?