I am guessing that unit had a air ride seat. Yeah it takes some time to get used to and with some adjustments it then becomes more comfortable. I did the same thing first time I drove a truck with a air ride seat about keeping a steady throttle. Could be worse....in a ag tractor I have the air ride seat automatically adjust for weight so it drops the air then raises it back up. Somewhat annoying and usually makes the seat too high. I'm thinking the steering wheel adjustment pedal is a standard thing in trucks. My older freightliner has a air operated foot button on the upper left side which is nice. The Mack is a cable operated pedal which is very stiff and at this time broken (waiting on a new cable that broke). Once you put some time behind the wheel it becomes second nature where the pedal is.