Yep. Sounds like flickering alright. Shows up especially in horizontal lines. Probably not bad with desktop (depending on wallpaper), right? But can get nasty with white stuff like a webpage or a spreadsheet. I suspect your modeline is giving you 50/25 instead of 60/30.
You're running projection TV, right? Have you calibrated it lately? Usually easily done with the remote. Helps a lot with clarity. Might help some with flicker by keeping the electrons focused "on pixel".
Good luck with it tonight. It's working, man; you're just tweaking it in now.