Welcome to iRV2.
Just a couple of questions .
Have you had the coach long enough to run a few tanks of fresh fuel through?
Stale gasoline can cause all sorts of performance problems, and any gas over a month old can be stale.
Do you have any service records? Has the engine been tuned up recently , fuel filter changed? Air filter?
As for the brakes, can you examine the rotors for any signs of rust ?
If the coach was sitting for any length of time, and the rotors have rusted, the rust will have to wear off before full braking will be possible.
That may not be the only problem, but worth considering.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.