Did they replace the flywheel by chance? IIRC, the SVT unit is a lot lighter than the stock flywheel. Not sure about the rest of the tranny though?? When you replaced the LIM, I'm assuming you used an SVT LIM which has bigger runners than stock LIMs. The port matching and alignment of all the intake plumbing can make a significant difference on how the engine runs. Our intake is pretty convoluted so any little kinks or bumps in the air flow can make a big difference. Try pulling it back apart and double check that every part matches up as perfectly as possible. Also double check the throttle linkage is opening the throttle all the way and that the TPS sensor is rotated through the full range. (It can be rocked back a couple of degrees to maximize the apparent throttle shaft travel.) Is the IMRC operating both sets of secondary valves correctly? Loosing a second wouldn't be fun.
