GMC Repair: 1994 6.5 turbo diesel, oil pressure switch, fuel pump relay

Question
QUESTION: I have a 1994 6.5 turbo diesel and while driving down the road at highway speeds 55 to 65 every once in a while the truck will miss or jerk no check engine or codes are gernerated.Any information on the above will greatly be appriciated. Thank You Raymond King

ANSWER: Hi
Does it do it at throttle, or steady cruise?
Is there ANY smoke at all if so what color?
Does it ever totally stall out? Does it start OK?
Are you having ANY other drivability concerns?
What maintance have you done? Fuel filter?
Air filter?
Did it just start doing this? Or has this been a long concern?
Please follow post back....
Will be waiting your reply
Pawl

---------- FOLLOW-UP ----------

QUESTION: Answer to your questions:
it does it at throttle when i let up on the throtle but it aalso does it at steady cruise but seems to be more subtle.
it happens so quick that I don"t notice any smoke and this problem dosen't happen all the time it is intermitent.it has never stalled out on me. the truck starts fine. I just purchased this vehicle from a used car dealer it has 95000 miles on it. I recently replaced the oil and filter the glow plugs the pdm mudule which is now mounted on a heat sink and not mounted on the side of the injection pump. I replaced the oil pressure switch and the fuel pump relay. the number on the injection pump is DS4 831 5521 That is the only drivability problem that I am having at this time. it started doing this right after I purchased this truck that was 1 month ago. Thank you Raymond King

Answer
Hi
The ONLY thing it sounds like you have not replaced is the injection pump.
USUALLY a code will  set if the pump is faulty.
It does have a DS prefix, so it is likely the updated pump could help.
Send me a private follow post I'll do do something for you.
Pawl