My 98 wrx is doing this atm. Spent all day changing hoses and cleaning things and nothing helped. After Getting bit ITSHY
I went and had a beer and started again
Checking everything started at the maf with a hose jammed in my ear i heard nothing but when i stuck my whole head in there i found that the pcv hose had come off and was sitting in a spot that looked normal. .. after reconnecting
The hose to the valve under tb the car runs like new. . Not sure if this helps much .