Hey Rob! Man ya still have snow up your way huh as I was in your neck of the woods on sunday. Hey how many miles do you have , And do you use additives like Howe's and do you tow? I have seen carbon buildup on injectors and I know they could'nt be performing too well. Those came out of a 24V that had 15K and the guy loved to lug the motor (High Fuel Low Boost/Rpm) and loved the sound (Until taught otherwise). When both my stock and DD1 injectors came out (12K on Stock and 22K on DD1's) They both looked new and people even remarked at the appearence of them. I use Howe's constantly. So Service life I haven't a clue (80-100K?)