FF - You don't say. If the plugs are still firing, what is your reasoning? Because the manual said so? I would agree with fluids and other necessary items but the dealer and the manual are in business to create ongoing revenue streams.

Judging by my gas mileage and how strong the engine runs pulling 8k lb boats and other equipment I'll agree to disagree. Thanks for the input though.

 

Yes, the manual. The plugs are a couple bucks a piece, so for $32.00 I would consider it preventative maintenance. Make sure your plugs are gapped corretly, dry and not fouled if you choose not to change them every 30,000 miles,
FF

 

Sound like the HEMI tick to me, check all you exhaust manifold bolts and studs and make sure they are all working. The only reason i can think that it happened after a tune up is that someone knocked them and broke em loose.