Tester could be right IF the oem iac has been removed and replaced with an aftermarket one AND you are experiencing a sticky throttle. The egr comes into the manifold right behind the throttle plate so a sticky throttle is common in these. The oem iac has a shield to keep the gunk off the shaft of the iac, aftermarket ones do not.
The intake manifold gasket is still the bigger problem with these. There is no support around the no 1 cylinder on the head side and only three bolts in this area. The power steering pump blocked GM from putting a bolt on the upper outboard corner. (stud and nut but who’s counting)