Assume from your coach signature that you have the Allison 3000 series transmission.
Let's drill down a little more into "what is happening".
When the engine is running and you go from "N" to "D" on the Allison shift pad, what happens? Do you get that slight clunk and if you release the brake does the coach start moving forward? If so, sounds like the transmission is doing its thing properly.
If throttle response is the issue, be aware some engines (do not know what engine you have) DO have a delay when starting out cold to keep drivers from hammering a cold engine.
So:
What engine do you have?
Does this only happen when the engine is cold or all the time?
