RE: Slowing down a PC-9
Say rjhpilot, what kind of rpm is your engine turning at idle? Is this ST a new engine? Are you using wood or composite props? At what altitude above sea level are you flying? And where do you have your plane balanced relative to the suggested C/G?
My second plane was a Seagull PC9 powered by an Irvine 51 (taken out by a glitch) a couple of years ago, another is in the box waiting to be put together (after I build my GP Ultimate 160). It is my favorite plane thus far, and although it does land faster than my trainer and some subsequent models I've flown; without flaps, I had no trouble getting it onto our landing strip (about 300 feet as well) with plenty of room to spare (never using more than 1/3 of the field, and never made a bad landing with the PC9. I just set up final and at idle let it fly itself until time to rotate the nose.
You might consider going to an 11X5 or even a 11X4 prop and also consider a wide blade prop. You might even try a 12X5 prop.You might also consider trying an OS F8 plug. Yes, I know they cost about $8, but I've found that they are worth it. In the last three years, and considering that in that time I've broke in some 5 motors, I've only gone through 6 plugs total, not bad considering the rich runs in breaking in the plugs and the effect that overly rich runs have on the coating on the plug element. With an inverted engine (and I have a tendency to set up the low end on all my engines a bit leaner than most people I fly with) but always have outstanding transitions, and few plug problems, you might consider your low end needle setting and your plug. And yes, I realize that your problem is with the idle speed, but that might be determined at least in part by your plug and low end mixture as well as your prop.
And if it is a roll-out problem, do consider putting a small piece of fuel tubing between the nose wheel and the collars on the axle as aussiesteve has suggested. If the airplane will fly as slowly as you say at altitude before entering a stall, it should do the same thing on landing. Just make sure you have a handle on it before getting it that slow low to the ground, and like I said, mine landed hot, but was not a problem in using up runway at all. I always liked the way that plane landed!!!
And remember, "Experience is a hard teacher. She always gives the test first, and the lesson some time later!"
Phillip