DRIVER456

I have SD tune for over a year and have not had a idle problem in awhile.I started running 100 octane gas when I go race and the temps started getting cooler,Thats when I think it started to idle funny,I think.The idle starts to swing and bounce from 500rpm to 1500rpm.I get it to idle fine in park,But in gear it bounce's,Then I get it to idle fine in gear and then it bounce's in park.So I figured let me put the MAF back on and see what happens.Long story short,I got it to idle pretty good,But not solid in gear,In park its rock solid.When I set {B0120}(EFILive) back to 4000rpm it bounce's again.So I have it set at 500rpm and it idle's fairly good.Thank God for Road Runner.Anybody have any idea's why it would not idle right in SD then idle's fine with the MAF back on? 427ci w/TSP giant cam................Paul