I have 92 accord with 98 Accord F18B engine. Few days back i pluged ODB2 scanner and short trim was 40%. Surely it indicates vacum leak i guess.

Also When i try to adjust Base IDLE i cant. On un plugng the IACV the idle starts bouncing which makes sure there is a leak

Funny thing is there are two screws on IACV when i loosen them and moves to one extreeme and adjust idle screw i can reduce the RPM to 650 RPM not below that. When i consider it base idle and reset ecu and plug IACV, restart car. it maintains 700 rpm but when i press throttle and leave the RPM First drops to 500 and then raises very slowly to 700.

Recently I got my Injector Cleaned and Flow tested.

I have two Questions.

1. Is my IACV bad or Vac leak is causing all this.
2. Can improper Adjustment cause Vac leak?
3. When car is turned Off I Block IACV Intake, Throttle Body filter place and EGR tightly and pump air through PCV Valve it keeps on going, why?