I have read about people having issues like this in the past. My sim only recently (I have made no changes in hardware) just up began to have this problem. Until this happened, MSFS had been running, well, as well as MSFS does. I throttle up to take off only to have the throttle back off to idle (any aircraft) and have to restart, resulting in the same issue. This is a game stopper I would like to solve. I also have always had intermittent rudder issues, with not being able to throw the rudder all the way right or left, but rather having it wag from side to side, being totally useless, but this is secondary to the throttle issue. I now cannot fly at all. I canāt remember if the throttle issue happened just after or before the latest update. I created a new control profile for my Honeycomb Alpha and Bravo from scratch to avoid conflicts. It also happens when the Bravo is disconnected. Please help! Mike
Any addons installed?
Remove EVERYTHING and try again
Take a look at the assists and make sure none are activated, and that your profiles / key bindings are correct.
Sometimes these things get reset after an update, which we just had with SU13.
Check that you have no assistance enabled (set everything to Hard/True to Life).
Then check your control profiles for everything that you have connected. Make sure you donāt have multiple hardware binding to the same controls. (for example, rudder control bound to your alpha and bravo hardware)
Hi. No assists; made a clean profile for the A&B controllers; tried both legacy and modern flight models. I cleared my community folder and deleted my rolling cache. Next time I started MSFS, it spent hours downloading the āmandatory contentā at the opening of the program, and still does the same thing, except on the DC-3, the left engine runs while the right one cuts off. Iāll try more aircraft later today; and Iāll try, oh, I donāt knowā¦weāll see. Thereās always P3D or X-Plane, I suppose 
Mike
I wouldnāt give up and spend money on something else so quickly because there is a reason this is happening. MSFS is just doing what itās told somewhere that you donāt know. Itās not like you are cursed or something.
Iām curious why your game had to download updates just because you emptied the Community folder. Did you check your Content Manager?
You definitely have something on your system giving contradictory instructions somewhere.
Hi. Yes, that does seem to me to be the likely source of the issue, as well. Iām curious about the upload, too. MSFS is like Windows itself, to me - full of promise, really cool, and just not living up to the hype. I was using Windows when it was mailed out in 3.5" floppys, and Microsoftās compression program was sued by and lost to āStackerā, as I recall. Oh, Iāll waste some time fooling around with things, and probably ultimately do a complete uninstall / reinstall of MSFS, to no avail, Iām sure. I hope it works again, as I really like the game, and have spent, like so many here, hundreds of dollars on add-ons. Mike
Also check all other profiles (for other hardware), there could be a conflict. Especially after an update, previously unused profiles could have been reactivated.
Hi; Well, I am back in the air, much to my surprise. I forgot about a joystick that I had plugged into my system. I disconnected it, and am back in the air. I am amazed. Thanks to all who answered my post. Mike
See what I mean? Whatever the case, whatever the situation, as hopeless as it seems, there is ALWAYS a rational reason for what happens.
This isnāt magic. Itās a machine and it just does what you tell it to do. Thatās all.
If you have āchecked everythingā, and canāt find the reason, the logical conclusion is that you have not checked everything.
Not singling you out specifically, just voicing a philosophy that has never failed me in 30 years of working with computers
I guess you missed this sentence 
Didnāt know it was connected, thatās why I didnāt check it initially. thanks anyway, though. I STILL have the issue with Logitech Radio Panel digits and cockpit radio digital numbers not lighting up unless I press my right mouse button, which showed up after the latest update, I believe. The aggravation continuesā¦Mike
Thatās exactly why you have to check everything, even the impossible. If the issue was because of something you knew, it wouldnāt be a mystery.
This is where the Control Options page is useful. Itāll show you every connected hardware by scrolling to the right. You can still connect the joystick if you want. But youāll need to manage it via the control options by switching to a blank profile.
What I do is I create profile for each aircraft that I fly with. So I donāt have to connect/disconnect hardware. Instead I just go to the control options, and switch all the profiles to the aircraft type Iām about to fly. Then just keep switching everytime I want to fly a different aircraft.
Hi, and thanks for the reply. Yes, I have a profile for each type of craft I fliy, as well. Still learning, and having lots of fun (read: aggravation). Wouldnāt have it any other way. Clear skies - if thatā what you want, anyway, haha - Mike.