Does BG Induction Cleaning improve gas mileage? on 2000 Ford Mustang

I used techron concentrate for 2 tank fulls and went from 18mpg to 19mpg and then 20mpg. Had a BG induction clean and went back to 18mpg. 150000 on my 3.8L Mustang. Used convenience store gasoline. Plugs wires, etc. are all good. Any thoughts will be appreciated.

Asked by for the 2000 Ford Mustang
who did the BG induction service , and was the car taken out on the highway and'blown-out' as some of us old schoolers would say.I've been in a shop for a while now that no longer uses induction services like that because of ignorance in proper procedures and the effects on a catalytic converter that's having excessive raw fuel dumped into it and then left to sit .In six months I saw my service mgr buy several cats(mainly one 'tech' who is no longer there was the cause BLAH BLAH BLAH ..........Anyhow check manifold vacuum at idle ,get ford parts (don't particullarly like fords but no matter ...FACTORY parts are always best! IF It's below 17" at idle in neutral w/no accessories on then my next scattered thought would be ....150,000 miles?timing chain wear? wobble crank pulley back and forth by hand ..if more than 5-7 degrees of play I'd start there .
Thanks for your response. The mechanic did take it out a run it on the highway to blow everything out. The car starts and runs fine. I thought I would see better gas mileage after the cleaning, but I suppose it basically just cleans out the varnish and carbon build up and makes the engine run better, not necessarily improves gas mileage.
Yes, if it's running better , I would expect better gas mileage , however it's a mustang. I don't know your age, but if it's running better , I might be driving it with a little more 'attitude' which might be taking away the gain in efficiency you got from the induction service. And it's a lot easier sell and more profitable than recommending replacing a worn timing chain and gears @ 150k , RIGHT?