My 1993 F-250 turbo diesel started "lugging" in 3rd gear on my last road trip. This made it impossible to drive 25 in the city zones, 2nd too low and 3rd lugged until 35mph or better. That was the only symptom.
I just ran to town and it did the exact same thing as I started on the highway and when I arrived in town. After one stop I headed home and it started doing the same thing in 2nd, 4th and a little in 5th, still very luggy in 3rd.
So it was only in the bottom end of 3rd and now is in all gears and luggs hard till higher rpm's, but I still felt it off in 5th all the way home. I went to town to grab the code reader I ordered and will plug it in as soon as the sun goes down.
Anyone had this occur.....seems to be more of an engine issue than a tranny issue....but I don't have a lot of experience with tranny problems. Thanks in advance for your input.

 

Of all the....Now I can't find the obd port, have looked and looked at google searches and forum searches and it just isn't there. Driver side fender by cruise control and hinge, on firewall. Also don't see it behind the glove box on passenger side. I am either blind or just ignorant, probably a little of both.

 

Ignorant, not blind, these trucks (the 7.3 IDI ) don't have an OBD port. Its a purely mechanical engine. The E4OD automatic transmission trucks had a computer to control how the transmission shifted, but nothing to do with the engine.

I agree it sounds more like an engine issue. Though I'm not sure where you point you for troubleshooting.... Check the air filter? Could be a fuel issue?

 

That might be the most beautiful thing I've ever read on the IDI forum- do you mind if I quote you in my signature?

7.3 IDI w/ M/T F-Series trucks were the last vehicles sold in North America with no engine computer whatsoever. If you look in the firewall you'll see there's a big square rubber plug where the PCM would go. For future reference, any 1992-1994 trucks with ANY powertrain combo other than the one you have, the OBD-1 connector is clipped to the fender near the brake master. Most 1987-1991 trucks had it there too but I don't recall which years and options it went with.

On a serious note, you probably have a fuel delivery issue of some sort. Keep an eye on the tailpipe, any observations on smoke or lack thereof may help us figure out what's happening.

 

The engine doesn't care what gear your in. The only input the engine cares about is how far the accelerator pedal is depressed. Although it only happened in 3rd gear originally, I believe that's a fluke. Your transmission is fine. If I were you, Id set up a 0-15psi fuel pressure gauge off the Schrader valve on the fuel filter housing and see what the fuel pressure is doing while you're driving. The engine driven Lift Pump tends to do strange things when they get more than 20 years old. I had a fuel pump that would just shut off while driving, the fuel system would pull a vacuum, and then the pump would start back up... I could see it on my Fuel Pressure gauge. It didn't affect drivability, thankfully.
Lucky for you, the high pressure fuel pump seems like its behaving correctly, but it may be running out of fuel at low RPM.
Just for a little background information for you; There are 3 fuel pumps in the IDI system. The engine mounted lift pump sucks fuel from the fuel tanks and pressurizes it to about 4PSI. On the back of the Injection Pump, there is a transfer pump that boost the pressure to about 80 PSI to keep the Injection pump happy. And then the injection pump increases it to ~2000psi to inject in the cylinder.
If your Transfer Pump and Lift pump are getting tired, it could be starving the IP pump.

 

never had lugging problem in my truck which is typically too low engine rpm for gear selection so id say operator error jk since these beasts like low rpms. i had similar problem of too high rpm for around town driving when i had 4.10 in rear end went to 3.50 much happier

 

So, I called a friend of mine that borrowed my truck about 9 months ago. I got to thinking this was only about 10 hours maybe of use by me on the truck since it was used by her. I asked if she had had any issues, as she was on a 3 day trip. She fessed up to having put gasoline instead of diesel at a truck stop, when it died as she was pulling into the lot, it wouldn't start, she tried several times before she realized what she had done. There was a repair shop at the truck stop that drained the tank and changed the filter for her. She said it ran fine the rest of the way home.
So I just ordered a new injector pump, glow plugs, injectors and lift pump. If I am getting into it, I'm changing it all. I'm about $1400 dollars pissed.

 

You could try changing the fuel filter again