OK - latest update.

I drove the truck home approx 4 hours. Still driving much better than it was prior to the injector replacement, but still surging pretty consistently. Not bucking like it was before.

It really does feel fuel or timing related. I have to give it a lot more throttle than I normally do to get it up to speed.

Kennedy - what is the best way to test the fuel? I've burned through almost a full tank with extra stanadyne grey added. Just refueled on the way home at a Pilot truck stop so I'll keep driving it to see if it changes behavior.

bshull - I was not aware of an inlet filter on the IP. Is it a screen type filter? Is it where the rubber line attaches from the filter housing? Certainly worth a try.

I still plan on replacing the timing chain based on the miles - opinions on chain vs. gears?

Thanks!