*LINK TO VIDEO OF PROBLEM AT END OF THIS POST
I saved this plane from retirement a couple of months ago when I bought it from a gentleman who had gotten out of the hobby about 7 years ago. I installed my receiver, and I changed out all fuel lines, and I installed brand new batteries. The engine started very easily for me, which shocked me since it had sat in an upstairs bedroom for a few years untouched. Over the last 3 weeks I have been flying it and enjoying the heck out of it! The 3W106B2 has phenominal power! ......well, it did.
Last week, on my second flight of the day, the engine sounded a bit like it was misfiring some at idle. The transition to high rpm was great, and the engine screamed, so I took off. It ran fine for a couple of minutes, then it suddenly began sounding like it was misfiring, and it lost a lot of power. Somehow it stayed running, and I was able to land safely.
Today, I changed out the spark plugs and checked the engine out. Everything looks ok to me, but I am still a little green to gassers. I've flown glow for 33+ years) I started it about an hour ago, and it fired right up, easily. It still sounded a little bit like something was not right at low idle; kind of like a misfire. But transition to high was outstanding, and it screamed! Then, I took a video of the second start, and it ran like crap. It is misfiring at all rpm ranges, and struggles badly. I don't know what is wrong, but I hate to see such a great engine have this kind of issues. I want to assume that it could be ignition related, but I don't know. I put in a brand new 4.8v NiMH pack, fully charged, and I did check the voltage, and it is good.
Has anyone had this issue with this engine? Any clue what I should do?
Here is a link to the video of what I'm experiencing..

This is all guess work. First, don't run the engine without the wing attached. Rebuild the carburetor. Change the ignition module. See if CH ignitions has one for you. It looks like you got a winner there. Keep us posted

I posted this on Flying Giants also, and one guy immediately spotted the problem. Many ignition units use 4.8v-6v packs in the past. The guy who read my post on Flying Giants noticed that I had a 4.8v pack on ignition, and immediately recognized it as my problem. I went to the Aircraft International site, and sure enough it says to use 6v-8v for ignition. I installed a 6.6v LiFe pack, and it solved the problem it seems.
Now, I do have a question for you... Why do you say not to run the engine without the wing? I realize that the canopy does add strength and support, but I don't think the wing does. Do you say this maybe for vibration dampening? Just a guess. I've been flying for more than 30 years, but I am still a bit green when it comes to 100cc and up. This is my second one in that range. Thanks for the help!

Without the wings you get to much vibration, the wings act like a vibration dampener.

That's what I thought you were getting at. Thanks for the tip!