Technical Chevy 6 with misfire at low speeds

It's bad lifters, imagine that....Look at this short video and when adjusted loose the engine runs smooth...I took it out oj the road and the engine revs nice and has much rpm and acceleration as can be expected...Time for new lifters...And they are a ***** to remove because of varnish but I getting them out. And the business end of the lifters look pretty decent ...

https://www.flickr.com/photos/75289626@N08/19024770541/in/dateposted-public/

 

Oh,I forgot to mention there were a few weak valve springs that apparently let a few lifters pump up at idle holding the valve open slightly.At higher speeds the effect was gone or lessened..
I replaced all the lifter and springs, runs like it should now...