Here is my $0.02 worth. I bought an early 99 F-350 new off the lot back in January of '99. It was a supercab longbed 6spd. When I bought it I hauled an 11' camper(4100#) and towed my Jeep on a flatbed. It was great. I added better shocks and airsprings to it because the camper pretty heavy, in fact when I was under warranty I had to have the cab repositioned on the frame from the twisting the camper was causing(so says the dealer).
Later I put a tuff country level kit on it and 315's. It looked awesome, but that made the ride even worse.
Now my priorities have changed I don't have the Jeep, and got rid of the camper for a trailer and have a baby on the way and the supercab wasn't going to cut it with a car seat.
I put gauges in it before I chipped it and it always seemed to have higher than normal EGTs. I couldn't find it and no mechanic I took it to could find a problem they all said it was normal(I could easily hit 1400 preturbo with no chip) After I chipped it I couldn't really use the power for the EGT I built. I changed the exhaust, put a bigger intercooler on, but still heat like a crazy bastard(easily 1600 pre turbo on parley's, unless I ran at 40mph in third gear) Also the turbo was surging like mad and the clutch was starting to slip. I had the "small turbo" that came on the early 99's which everyone said shouldn't surge, but it surged like crazy. On my last trip my friend out pulled me and out mileaged me (I was getting 8.5-9 towing 8500#) with his 05 6.0 GMC, both of us towing a similar trailer.
I have a hard time believing that too, I honestly think I had a problem with my stroker that hadn't really showed itself yet(maybe injectors, or HPOP or similar), but I was tired of dinking with it.
Here is what I liked about it:
1. power when new
2. mpg when towing when new
3. looks (aka growl factor)
Here is what I didn't like about it:
1. I always seemed to be spending money on it. Usually little stuff, but still money being spent(100-200/month).
2. The ride sucked a$$.
3. The stock clutch was a beast.
4. Ford's hydroboost steering sucks, I can actually steer my GMC in a parking lot
5. Ford's ESOF sucks A$$. I can't tell you how many times it either popped out of 4L pulling my camper/boat out on the ramp or wouldn't go into 4x4 due to the auto hubs, that really sucks in the snow. Of course the dealer never found anything wrong.
6. God help you if you need to take it in for repairs, get your wallet out!
Obviously, I remember more bad than good otherwise I wouldn't have kept it as long as I did.
Here is what I would do if I were shopping for a powerstroke.
1. Get a crew cab
2. avoid the early 99's. They had a cat convertor and depending on where you live some counties are bitches about it(aka Davis) and that really limits your exhuast options. Some later models (6spds) had cats too so be sure to look and maybe even have the vin pulled to make sure you don't have to buy one($500-800) come IM time because someone illegally removed it.
3. The early 99's had the small turbo as well and that spelled trouble in the aftermarket should you need one. Almost everybody makes the 99.5 and up turbo. The early truck can be converted, but that takes quite a bit of work.
4. After 2001 sometime Ford went to different rods in the block and can't hold up to extreme power building( the early ones had forged rods).
5. If your going to chip it get a manual and live with the shifting, otherwise be prepared to rebuild the trans soon.
Aside from my long negative rant they are good trucks, I just had something weird with mine I honestly believe. Just carry a spare CPS in the glove box. They eat em up pretty good sometimes.
I ended up trading for a crewcab GMC with the 8.1 gas motor. I doesn't pull nearly as strong, but its more comfortable and gets nearly the same towing mileage. I'm pretty sure when I find my money tree I'll be looking for a duramax, but for now this crew cab serves me better than my supercab.