I think the MAF is a little too close to the air filter. Most other intakes give the MAF at least an inch or two of straight piping to allow the air flow to even out a little bit. older GM MAFs have a honey comb shaped screen to try to create a laminar flow. So, there might be too much turbulence where it is at right now.
Also, if the inner diameter of the pipe where the MAF sensor goes into is different than the factory ID that will mess up the MAF because the ECM is calibrated to that MAF with a specific diameter pipe surrounding it. Changing the diameter of the pipe around the MAF alters the flow characteristics.
So ditch that MAF housing if it is not the same diameter as stock. If that isn’t the problem, try getting some pipe and maybe a few more silicone couplers and clamps to add some inches between the MAF housing and the air filter.