a properly tuned engine will load up eventually.. it is actually a good sign if it idles a bit high then goes to a slower idle.. if anything.. richen your top end.. it sounds like it's coming off wide open throttle a little lean and then getting fuel back at idle..
I'd richen your top end up 1/4 of a full turn.. and retune the top to where it just starts to scream.. you are probably close to where you want to be.. what more than likely happened was you tuned your top end to power then tuned your low end without richening your top again..
when I tune.. I start with both needles at a noticably rich setting.. I tune the top end to power.. where it "begins" to scream.. then I richen it 1/4 turn then tune the low needle to where it will idle for 5-10 seconds and still have good power off the line.. but will load up after any more idle time than that.. it usually all falls into place after that.. but sometimes the top needle needs to be leaned 1-2 more hours after that..
hope that helps.. if you plan to retune completely.. put a full turn out on both needles and start over.. it's not uncommon to have to retune an engine.. I do it every time mine is out