driving down the interstate at 55 or higher it starts to shutter also on an incline. replaced the wires, plugs, maf sensor fuel filter. any help? please

When you say Shudder you mean the entire car shakes or you can feel the engine shake through the steering wheel and pedals? if its anything like mine could be cv transaxles, or your trans cant handle the load of uphill or high speeds (same area). Check your coil packs, might not be able to put out the right spark under load. Amateur guesses here even more blindly seeing as its boosted

Is this more of a surging? Could be your TCC solenoid switch. There'* a write up on that in tech info. It'* easy to adjust.