I have a few questions.

1. If a car has about 140k miles on it and it idles very roughly, what kind of fluid do i put in to make it idle smoother? Or is it something else?

2. What is the best kind of fluid to use to clean injectors?

3. To regain power, fuel efficiency, what are all the fluids I need?

thanks.

 

On One?????????!!!!!!!!!

 

Do a full tuneup (plugs, PCV valve, air filter, fuel filter, oil change), clean the TB & IACV, put Chevron w/ Techron Fuel System cleaner in the tank, and use Sea Foam to clean out the engine a little. Maybe something else

If your MPG is bad then maybe the O2 sensors are dying or "slow"

 

That is exactly what I would recommend (JaTaN was reading my mind). Techron and Seafoam are both very good products for their intended purposes. When getting the Techron, keep in mind there are 2 different ones in similar looking bottles. One is more concentrated than the other. The concentrated one is the one you'd want. I think the "watered down" version is called Techron Pro-Guard or something like that. The good stuff is slightly more expensive.
Use the Seafoam sucked through a vacuum source. I use the one right by the IACV so it gets evenly distributed to all intake runners (the other end of this vacuum line connects to the EVAP purge control valve or something like that). After letting it sit for the recommended 5 minutes (I do 10-20), watch all the smoke when you crank it up. That alone is worth the $5.00 or so!

Dave