Ford 7.3L Power Stroke (1999-2003) :: Engine Code P0683 - Surging / Near-stalling After Starting And Hiccup At Speed

I have a 2000 Excursion with the 7.3L. We bought it in February of last year with 81,000 miles on it, and it has 111,000 miles on it now.

First problem:

It threw a code today: P0683 indicating a communication issue between the Glow Plug Control Module and PCM Communication Circuit. Other than the code, the truck isn't doing anything out of the ordinary today. Drove it about 40 miles, up to 80 MPH, problem three below did show it's head once, but other than that it ran great.

Second problem:

Ever since we've owned the vehicle it has done a strange surging/near-stalling thing (for lack of a better word) when it's started up. It only does it occasionally, and the problem seems to appear, and then go away for several weeks or months only to reappear. Here's how it goes:

- Start truck
- After starting the truck immediately begins to surge (rev?) and then nearly stall.
- It will do this over and over, about one surge/near-stall cycle per second, until I tap the accelerator, at which point it stops immediately. So far it has never stopped on it's own, but has always stopped with a tap of the accelerator.

Up until recently I chalked this up to "huh, that's weird" since the truck has otherwise run fine.

Third Problem:

Every once in a while the truck will hiccup while it's up to speed. It only seems to do it at highway speeds, typically between 55-70, and the hiccup typically only occurs once.

The first time I distinctly remember it happening was right after I had replaced the Camshaft Position Sensor (approximately 5-6 weeks ago).

While digging around online I found one other guy say his truck started doing the same thing after replacing the CMP in his F250 with the same little plastic gray one I used. So that problem might be caused by that part.

My Thoughts:

It seems like the run-away favorite for fixing problem one is to replace the GPCM. I've dug through a couple hours of forums this afternoon/evening, and it looks to me like the GPCM is the culprit the vast majority of the time when code P0683 comes up.

I'm thinking problem 2 might be an ICP issue. I can't find any previous forums anywhere that describe the exact issue I'm having - or really anything very close. Maybe it's out there, but I couldn't find it. So I'm really grasping at straws.

Problem 3 could either be related to the ICP (if problem 2 is an ICP problem) or it could be due to the new CMP I installed (the cheap gray plastic one from Autozone). It's possible the hiccup has been around longer than I think. Half the time when it happens (or does it?) I can't decide if it was a hiccup or a bump on the road I didn't see. I am sure it's happening at times, but there are other times I'm not sure if it was a hiccup or a bump I just didn't see. So I think it's possible it's been going on longer than I realize, and I noticed it that first time because I had JUST been under the hood and pretty finely attuned to how the truck was running as a result.

I'm about to hitch my 35' camper to this truck and haul it a few hours and I'm not feeling real confident right now. Problem 1 hit today, problem 2 is more prevalent than every right now, and problem 3 has been hiccupping for 5 or 6 weeks. I'd like to get at least problems 1 and 3 sorted out before hauling 8,000 lbs if possible.