One thing you have to understand is that nitro engines need to be tuned each & every time you run it. You cannot run a nitro one day and expect it to be in tune the next. I'd say this is all you are experiencing. I am thinking that since you richened it up a fair bit the night before has left it very rich for the next day. It all depends on the weather. A tuned setting one day may be too lean or too rich the next. So I'd try leaning back out the HSN first and see if that helps.

You say its idling but when you throttle nothing happens? Does it rev but not move? are your throttle linkages all working? Is there any raw fuel coming out of the pipe? Its sounds rich to me and I'd lean it again. If it gets worse then its probably the opposite & too lean and you need to richen it up more.

Just sounds like you need to do some fine tuning thats all.

I quick test to see if the idle mixture is set right: With the car off the ground, give the throttle a firm squeeze, maybe 80% throttle. Listen to how the engine responds and how it "settles" back down to idle. If the idle racers or increases before settling down its too lean. If the idle suddenly immediately drops & starts to bog down its too rich. Ideally you want it to settle down into a steady idle for abount 20-30secs before bgging down. If you think its too lean, then richen the LSN and if too rich, lean out the LSN.

A simplistic outline: HSN for maximum speed/performance; LSN for throttle response and idle mixture.