Truck top speed 72 now 67 after new ECM

1999 Freightliner Century S60 12.7
-just replaced all injectors, injector harness, ECM, TPS sensor.
Truck before Freightliner repairs had top speed 72 now after repairs, only goes 67 mph AND THEN after 15 minutes of driving goes 72 mph while bobtail.
Truck occasionally will go 72 mph while loaded, but it’s rare.
If you guys have any ideas of what it could be, I would really appreciate it. Thank you.

 

Yeah, so I wonder why I can only go 67 MPH right after starting truck, but occasionally 72 MPH after a bit. I changed TPS, didn’t help.

 

That’s what I was thinking, but it only gets to 72 when bobtail or rarely loaded. Seems like if it was missed programming, it wouldn’t get back to 72.

 

This could be it, even though the MPG is about the same as before when I was doing 72 constantly loaded/empty. 6.3 mpg previously / 6.5 now.

 

That sounds almost exactly what’s going on. I typically run 2 roads from Shreveport, LA to Lubbock, TX. The truck starts at 67 mph, after 15-20 minutes, then allows me to set cruise at 72 but on a hill it may drop the cruise down to 67 again, until I set it back to 72. I’m going to see if I can get someone to look at the parameters in DDDL and see if “Efficiency Mode” or something is on. Thanks for the idea Big Road Skateboard.