I have a '94 Chey K1500 withg a 6.5 L Turbo Diesel. I have run it for five years with no problems and have been keeping up with the maintenence. Recently, though, it has been stalling at the most inopportune moments. It seems to stall mostly in the mornings at stop lights or when idling. However, it has also stalled out at about 1500 RPM a couple of times. I replaced the fuel filter 150 miles ago and the problem went away for a week. Now it is back. When it stalls it has no problem starting back up and runs fine when completely warmed up.

Could it be the feed pump? I have never replaced that. Is there a way to test it without spending 100 bucks on a new one?