Do not have a IQ110 but from my readings here on the forum. Try getting the pit almost to desired temp before closing off all the vents and letting the iq110 take over. The initial burn and coming to temp takes up alot of air. Maybe the reason why it takes so long to come up to your desired temp.
Give it a try.
Leave all vents wide open until the pit comes up to 265-275 than start closing the intake vents down while still leaving the exhaust fan wide open.
Set the iq110 to 300 degrees and it should take over and get the pit there and stabilize.
Q-ING on my: PBC, Weber OTG & Cookshack Smokette - Temped by Thermoworks TW-8060