base timing keeps advancing by itself...

Only other thing i could think of is fuel quality… maybe varying octane in the garbage 87e10 i feed it?
You are going to have a difficult time trying to develope a tune using 87 octane fuel with 10 % ethanol, been there tried that. You may solve some of your issues by upgrading to non ethanol 91 or 93 octane fuel.
Whats the compression ratio?
Show us some pic's of the plugs.
The cheap *** fuel may be causing the detention.