Small Engines (Lawn Mowers, etc.): Craftsman 10HP engine problem, throttle settings, electrical problem

Question
Sorry this is so long:

I have a craftsman 10HP Tecumseh rear engine riding mower. Ran okay when I got it (slightly
used), but when running the engine at mid-to-high throttle the engine seemed to "skip" once
in a while. No backfiring, just a small misfiring that would cause the engine speed would slow down a little, then it would recover and speed up again. It would cycle like that constantly when running at high RPM.  

This season the problem seemed to get even worse, as if it were runing lean at anything off of idle speed. Idled fine, but as soon as you rolled on throttle, it stumbled and backfired and would stall unless you back off throttle. So I tore down the carb, removed main jet and idle jet and cleaned everything out with aerosol carb cleaner and blew it clean with compressed air. Runs a little better now but still not 100% at higher throttle settings. Sounds like it is running lean. This machine has a "fixed" type main jet and idle jet, and all passages and jets in the carb are now clean. There is no in-line fuel filter, and fuel flow to the bowl is excellent.

So yesterday it ran well enough to use it to mow, but now I noticed last night that whenever the transmission is put into reverse, the engine stalls! This happens with the clutch depressed, as soon as you shift into Reverse. There is no "drag" on the engine when it happens; it sounds like when the engine is turned "off" with the key, and unless you shift out of reverse quickly, it will stall. Help!

Answer
Hi Dave,

It sounds like you are making progress on the engine running problem.
There should be no reason for the engine to stall when there is no load on it.  This indicates an electrical problem.  You DO mention about it sounding like the key is turned off.  I suspect a faulty safety switch.  It may be located in the seat or on the shifter or both.

Let me know what you find.
Michael