Throttle body cleaner

Our '97 Blazer was picked up by a tow truck last night. Just a few days ago we had the engine replaced with one from the junkyard. Last night the starter would crank the engine but it just wouldn't start. My wife cranked it for fifteen minutes until the battery went dead. The tow truck operator jumped the car and removed the air filtration system and stuck a screw driver down the center of the engine - then he started the truck. I guess he was just trying to get extra air in the engine. After that the engine ran great, even at idle, and I drove it to our mechanic's place.

The tow truck operator recommended I use some throttle body cleaner on the engine. He recommended a product called "44k" from a company named "BG." Here is the link:
http://www.bgprod.com/bgconsumer/bgservices/44k.html

Can anyone vouch for this product, or something like it? It is an additive that gets added to the gas tank that "cleans" the engine.

I poked around their web site and noticed they have another product called "Supercharge II" that is supposed to be added to gasoline every tankful to keep the engine clean.

BG claims they have a 1993 Mazda MX-6 with over 310,000 miles on it but the engine is in like new condition. They pulled the engine apart and claim everything is within new from factory limits. They used their synthetic engine oil and they used their gasoline additives from the time the car had 60,000 miles up until 310,000 miles. Here is the link to the test:
http://www.bgprod.com/bgconsumer/tdc.html

I wonder if this is really a good idea to add to our trucks or if I should steer clear of it. The tow truck operator seemed knowledgeable but have any of you had bad experiences?

Thanks,
-- recurve