I'd use BG 44K before Techron (& especially before "several tanks full with techron"!). It's the "prescription strength" cleaner & only needs to be used once every 30k miles or so. I talked a Saab owner into trying it when the dealer told him he needed to replace one of his injectors (~$450, IIRC), & he said it cleared things up by the time he'd gone thru 1/2 a tankful.
