same thing was happening to my friend and it was because he had it set up for 302 firing order and not the 302 HO firing order which is same as a 351...
I went with an older Paxton SN 89 ball drive....
I have a 3.75 pulley on it and get 8 psi. No dyno #'s yet. Its self contained, easy to install and CHEAP on ebay (under 1000) and you can rebuild them yourself if it goes bad ....
alot of people recently with the same idle and running problems just as myself...
I replace the meter yesterday and it is infact running better but I still believe the problem is there