I know I have different cams but mine looks to be around 780 and it likes it. 840 seems a little high to me.
And like Andrew said, dyno tune smoothed everything out.
Mine DID idle fine when I was running a dataloged tune but I also had cam bucking in low rpm situations pretty much daily.
08 GT 5spd
Spectra CAI, Comp Cam Detroit Rockers, Kooks headers w/catted H-pipe, Revolution Automotive dyno tuned, FB430 race mufflers, 3.55s, JLT catch can, BMR Lca's and relo brackets. Prothane motor mounts and sway bar bushings.
20% tint, smoked markers and tail lights w/sequentials. Clear front signal covers, series 3 chin spoiler.