This weekend my 06 LS with just 50k miles started to hesitate and shudder right about 2k rpm. Happens in 4th and 5th gear when the engine is loaded for mild accelleration. Any sharp acceleration will drop a gear and go but that 1800-2200 range has started to buck. I'm assuming this is coils even though only 50k on the clock. My v6 lasted till 85k before I changed them but this LS is 10 years old now. Where can I get Motorcraft coils and plugs? I understand Accel is also an option I should entertain. I want to do it right, no cheap stuff.