1): A 461 comes with Carb Limiters, the richest the dealer can set the Hi is 3/4 turn out. This is not rich enough for a Max Flow and DP Muff Cover. You must pull the limiters on the carb if you are going to run it this way, or you will burn the saw up. For your set up, I would start by setting the Lo at 1 full turn out, and the Hi at 1 + 1/8 turn out. Then as the saw warms up, tune idle and Hi by ear. At WOT, the saw should break up or the Hi is not rich enough. If it does not clean up in the cut, it is too rich.
2) Pull the Filter cover and the filter. Make sure your control lever is operating properly. All the way down should close the choke (fully). Fast Idle should leave the choke fully open (there is no such thing as half choke) and open the throttle butterfly a bit. Run should have the throttle butterfly closed. Stop shots out the spark.
3) If your saw pops on choke, then does not start within 4 pulls on Fast Idle, there is something wrong.
At this stage of the game, I would put the stock stuff back on the saw and bring it to the Dealer.
461s are generally VERY RELIABLE, they are used as the "RESCUE SAW" by Fire Departments, etc. Hope you did not damage it with your air filter and muffler mod, (w/o pulling carb limiters).