OK just noticed something. In the garage I mostly had the top cover off and replaced to drive. Just noticed when the top cover is on, MAF tilts and pulls out of rear spring clip. Just replaced and lubed all airway seals and made sure all MAF clips were in place. Now have 20.4 in-hg at 700 rpm idle in Park...but when I turn the AC on it drops to 17-18 in-hg. Turn AC off and comes back up. Is this normal or do I need to start looking for a leak in the HVAC system ?