Alright, I know this topic has been beat to death all over the web. But i just cant seem to find a thread with a similar problem as mine. So I'm gonna ask for some help here.
The truck is a 1999 24v, its my main tow rig, barr bones stock and has never let me down until recently, and with 411, 000 miles on the clock I'd say that's not to bad. The truck took to fits of running fine one minute and not starting the next. Left me stranded a number of places. I replaced the pump, tested the fuel pressure and the vp44. Hunted for hours for a bad wire, tried a differnt ECM and nothing helped. Mind you there is no codes, the tachometer was working fine and the truck ran great ahen it did start. So I decided to replace the crank sensor. What a nightmare... took me 8 hours busting it up piece by piece with a chisel. New sensor installed and the truck starts every single time with no hesitation. BUT its starts the tach comes up to idle the truck runs just the slightest bit rough for about 5 seconds. Then the tach drops to zero the engine smooths right out and runs good but only with about half the power of normal. It sill barley get up to 55mph with my camper behind it... I'm STUMPED. Any help would be great!
Thanks

 

Was your crank sensor on the lower left side of the block about half way back? I wonder if there is a clearance issue with the sensor picking up the crank wheel.
Are there any codes now?

 

Yes it is have to remove the starter to get to it. Waiting on a code reader it.does have a code now as off this morning. I'm thinking its a faulty sensor just a duralast cheapy from autozone

 

Any Updates?

 

Still no luck. Still throwing the CKP code and p1688 for derating power. The truck starts up fine then engine flutters just enough to notice for about 5 senconds, then the tach needle drops and the engine smooths right out. But it is very obviously in limp mode. I'm beggining to think pcm problems. Not sure were else to go from here..