I just had that same problem and it was the lower intake gaskets. My VX was bucking like a bronco and would stall after it got really bad. It would run good enough once it got going but under idle it was horrible and eventually started throwing lean codes.
Try shooting a little carb cleaner around the lower gaskets and the top one, if it revs when you do it it's sucking air through there. It ran me $250 at a local shop to have all three gaskets replaced. (probably a good move anyway since I plan on SCing soon.) I'd look into a new timing belt too while it's in. It's relatively cheap insurence compared to the cost of a motor.