Idle issues with Fast 102/102

Hi guys, I have a 99 Chevrolet Silverado, it originally had a 5.3 and after about 220,000 miles we decided to pull that motor out and take a 6.0 truck motor and stroke it to a 408. Anyway we went with a pretty mild build, comp 224/220 camshaft, 42lb injectors, etc.. Anyway we are really having some issues with idle while trying to use the FAST 102mm LSX intake manifold and throttle body, the truck will randomly act up while trying to switch between gears and it dies all the time, if we don't wait for it to idle down it is extremely hard to get it to go into gear and it seems to take a very long time to idle down.

We have been through 2 tuners, the latest tuner is using HPtuners, but he seems to be having similar problems. I am looking for any advice possible on where we need to look to get this thing to idle correctly, if we can't come up with a solution we might just put the stock throttle body back on it. Anyway im looking for any advice possible, I appreciate it!

You need a tuner to take there time tuning it .maybe even leave the vehicle with them if possible.and if they say they can't tune it look somewhere else.

FAST intakes are a bitch. No better way to say it. You need a top notch tuner, and a few hours of their time. Also make sure you have no vacuum leaks and the like.

I worked it out... had a ton of different probs with my FAST LSXrt... running stock tb though. idles great now