Ok, I have an 01. Lets see
I pulled the TPS out of it, backed the idle validation switch off a whole bunch, and advanced the tps to get rid of the dead zone at the bottom of the pedal. I gutted the EBPV and the actuator in the pedestal, and sealed it up, put on a NAPA 6637 air filter, bumped the fuel pressure to 70 psi idle and about 63 WOT. Cleaned off the muffler, put in a chunk of straight pipe, modified the fuel pickup in the tank, to eliminate the 1/4 tank issues, got rid of the "mixer" in the process, and replaced all the hard lines with hoses.
The thing was a dog originally, and after all these little things, it was almost respectable. not quite, but almost. For heavy towing, I am sure that TW or PHP could come up with something to make a 550 work. Funny how low the gearing is, and yet they still won't pull the scum off of warm rice pudding.
I lost #7 cylinder in mine about two months ago, but it had been problematic for a long time, the engine was supposed to be a reman long-block, but it was obviously a used and abused engine out of something else. I cannot see anything minor having a negative effect on it.
Good luck with yours, let me know how it turns out.