Engine skip between 1400 and 1600 RPM. Anyone near Chicago?

[RCS15150]

Hey everyone, just wondering if anybody is located around Chicago maybe within a couple hours to help do some injector work on my 02 F250. #3 and #8 came up on the contribution test and I really think the Injector O-Rings need to be replaced too. Really want to do the work myself but do not want to mess anything up. I would of course pay by the hour. Truck runs good until it heats up, then the motor makes a sputter/clatter/skip noise between 1400 and 1600 RPMs. No real signs of power loss at all, just driving me nuts. Truck runs good when warmed up, but not in that RPM range. Anyone got any ideas of what else it could be? Let me know if anyone who knows what they are doin wants to make some extra cash. Thanks!