sluggish in 4 on the freeway

[sixfour4x4]

got a 350 mated to a sm420 4 speed w/ granny gear in my 4x4. down shifted into 2nd on accident and got a temporary 7.5k on the tach sounded baaaad. then on the way home i'm driving fine on the street through 3rd gear, then the freeway and as soon as i hit ~60mph my motor became sluggish, down to third...still sluggish...back to the street and fine even in high rpm in lower gears. also fine in rpm range in neutral. chime in?

[Eagar1]

You may have lost your vacuum or mechanical advance, or stretched your timing chain. I think you would have known if you floated a valve or bent a push rod or two.

[TheDark1]

I used to blow out mechanical fuel pumps like crazy when I over reved. I used the cheap-o ones because they had a lifetime warranty. After the fifth one I switched to an electric one and the problem went away. Mine was the same way, lost power under heavy load, but would pull through the lower gears fine.