I have never heard anyone actually recommend this gunk engine cleaner before. I have heard several bad things about it, and that it is basically just diesel fuel. Me personally, I would never put anything in my engine oil other than oil. The only way I would ever consider putting anything in there that was not an oil was if I was to pull the oil pan afterwards and let it all drain out, since during an oil change the oil never all drains out; you can have up to half a quart left in the pan in most vehicles after draining. Just my 2 cents.

Check the other items recommended first, O2, IAC, throttle body, etcà

Sean