You need to ditch that filter and currogated hose setup, it can't be helping... and I haven't heard anything good about spectre filters... My setup isn't fantabulous but it's worked for years...
That was a long time ago but it's a factory filter box from a 2.9L pre MAF Ranger so it had a hose barb on the lid instead of a MAF flange, I grabbed the intake tube from the junkyard too to cut up to fit my needs... I scabbed a mount for the VAM out of some 1/8" aluminum I found that attaches to the battery box. The splice in the upper elbow part where it's just two rubber hoses clamped together does have a short piece of PVC on the inner piece that's angled on both sides so it's not a restriction. I have a K&N filter in the box since I had it around... the stock filter box is the same filter used on a 4.0L so it "should" be a reasonable amount of air, and since I used the stock intake ducting in front of the radiator it's still getting cold air. I should put a vacuum gauge on the inlet of the turbo to see if it is a restriction...
You can also see my conversion upper hose to use V6 radiators, I'm pretty sure that's the original 1990 upper hose... I just cut it in half and put a copper elbow in the middle... works great
I am curious if the intercooler helps at all, I bet it does something... I have one somewhere, I should put it in mine...