With an 86 Nissan truck I found that by using resistance on the TPS and the CHTS I could lean it out...but saw no real mpg gain by doing so...some power loss...and might have been overheating it.
I put a bypass switch on the CHTS resistance so it would start in colder weather...and I could lean it out so much with the TPS resistance...that it wouldn't run.
I used small pots that I put into a panel on the dash...adjustable while driving.
This kind of thing might work if you had additional mods like fuel vapor or ????
And each vehicle is different?
http://www.nonags.org/members/nijqk/Sensor%5Fmods%2Edoc