1995 Camaro 3.4 v6

With the vehicle in park or neutral not much load on the engine. When you put in gear, there is a load. The info is code 35, idle speed error, the main thing I wanted you to notice was system too lean or too rich. Now, there could be other issues, but, I wondered about fuel trims, running rich or lean. I also wondered cylinder compression? You can clean throttle body and iac, see if it helps? I did look at fuel pressure, 41--47 psi so if about in the middle, should be fine.