MAF Sensor Half Duct Taped Over?

I bought a 2001 330i in September of 2016 and have slowly but steadily been working on upgrading/repairing a number of aspects on it. As of this last week, living in the Portland Metro area I had to take the car into DEQ to pass emissions before being able to renew my registration. However, the OBD-II reading spat out P0171, P0172, and P0175 codes (seems oxymoronic on Bank 1) and thus I didn't pass. Upon searching the internet and various forums and threads, as well as placing a call to the shop where I've had my coolant system rebuilt, I've discovered that most likely the problem existed either from a leak in my intake system and/or a bad/dirty MAF sensor. Thus my first step was to clean the MAF sensor and see if that fixed the problem (cheapest solution). The previous owner had a K&N "CAI" installed that was merely an exposed cone filter connected directly to the MAF. However, upon pulling the two apart, I found that the bottom half of the sensor (the opposite half from where the actual sensor is) was duct tape covered, seemingly only letting half the air in. Strangest thing I've seen and have yet to find any information on.

So I took the duct tape all the way off, cleaned the sensor, and reinstalled the pieces. However, upon starting the car then, it severely rough idled. RPMs were jumping all over the place from <500-2000 and the car was shaking like it was having a seizure, wouldn't take any response from the gas pedal, and after 10 seconds killed itself. Further research suggested I unplug the MAF sensor to find out if it was faulty, and sure enough upon starting the car up again it had no issue. I've done the inspection further down the intake line and found a couple of cracks and am in the process of replacing said parts and the DISA gasket. As far as cheap (at least cheaper) fixes go, I'm going to put in the stock air box and try that out with the current MAF sensor. Has anyone else ever seen or heard anything about duct taping/covering the bottom half of the MAF sensor? Is this a sign that the sensor is bad and is a MacGyver fix? Solutions?

MAF Sensor Half Duct Taped Over?