Adam do you have a spare ECU and coil that you can sub in or take em off of one of your other running vehicles. since you have the P you'd also need a regular electronic dist or another point one/ballast for a quick test. I missed the obvious, that a vac leak would not be part time unless something is loose in the booster check valve if PB or possibly the PCV (clamp it (hose) shut will elim that). & the P install inside the cap is correct right (nothing loose/moving that ain't supposed to be)?