Attention: TDR Forum Junkies 
I actually have two problems that started about 6 months ago. Here is the order of events.
1. High Pressure Pump replaced by dealer with factory rebuilt one. Approx 1 year ago.
2. Clutch replaced with new one from TST 6 months ago.
(After getting the truck back after the clutch replacement notice slight occasional miss in engine. Very minor but especially noticeable when standing by the exhaust pipe. )
3. Last month take truck in because Tach keeps dropping to zero but it runs just fine and doesn't seem to affect the driveability of the truck at all.
4. Dealer says it is a bad Crankshaft Position Sensor and also a bad MAP sensor and they replace both. I get the truck back and notice a surging problem at 1400 RPM 1600 RPM and 2100 RPM. I also notice that unlike before the Tach needle jumps in about 50 RPM increments when accelerating or even at idle when racing the engine. Rock solid at idle. At 1600 RPM it fluctuates about 100 RPM.
5. On my own I buy a second MAP sensor and replace it and also pull out my DD3 injectors and have them all tested locally. Neither of these things make any difference. I also checked all the wiring on the MAP sensor leads and on the Powermax 2 box. I even removed the PM2 and still had the problem.
6. The other night while is was idling I sped up the motor some and the ABS light came on for a second then went off.
My main problem is the surging which is really irritating but I also would like to fix the slight miss. I tried taking it back to the dealer and they said they didn't know what it was. They act baffled by my modifications.
Truck Specs:
98. 5 24v 5 speed, Reflashed ECM by TST, PM2, DD3 injectors. Rear ABS only.
1. High Pressure Pump replaced by dealer with factory rebuilt one. Approx 1 year ago.
2. Clutch replaced with new one from TST 6 months ago.
(After getting the truck back after the clutch replacement notice slight occasional miss in engine. Very minor but especially noticeable when standing by the exhaust pipe. )
3. Last month take truck in because Tach keeps dropping to zero but it runs just fine and doesn't seem to affect the driveability of the truck at all.
4. Dealer says it is a bad Crankshaft Position Sensor and also a bad MAP sensor and they replace both. I get the truck back and notice a surging problem at 1400 RPM 1600 RPM and 2100 RPM. I also notice that unlike before the Tach needle jumps in about 50 RPM increments when accelerating or even at idle when racing the engine. Rock solid at idle. At 1600 RPM it fluctuates about 100 RPM.
5. On my own I buy a second MAP sensor and replace it and also pull out my DD3 injectors and have them all tested locally. Neither of these things make any difference. I also checked all the wiring on the MAP sensor leads and on the Powermax 2 box. I even removed the PM2 and still had the problem.
6. The other night while is was idling I sped up the motor some and the ABS light came on for a second then went off.
My main problem is the surging which is really irritating but I also would like to fix the slight miss. I tried taking it back to the dealer and they said they didn't know what it was. They act baffled by my modifications.
Truck Specs:
98. 5 24v 5 speed, Reflashed ECM by TST, PM2, DD3 injectors. Rear ABS only.
He said the diesel guy had gone home and didn't work again until monday but that they could do basic stuff like getting the error code and replacing sensors without him. I am dying to know what this is. Part of me is thinking the accelerator position sensor but I replaced that about 2 1/2 years ago and when it went bad the truck would idle just fine. 
