My JDM 1995 AE110 has 5A-FE 1.5L engine which mostly run on CNG fuel. Recently I had idling issue, cut off at stop, dash and steering wheel shaking at Stop idle etc etc. Well, it's all OK now, it was the faulty distributor. BUT, here is the issue..

When I bought the car, the engine did not have EGR valve (or EGR system which includes necessary vacuum lines and all). It had VSV system, MAP sensor but not EGR. No check engine light.

Now, my mechanic did manage to stable the idle both with AC and without AC. But he did change the vacuum system- I don't know exactly what or where but he removed the original VSV and installed something that also looks like VSV. A pipe came into the EGR. The MAP sensor is there. I just have seeing that ugly looking EGR thing.. looks like a metallic mushroom grown near my throttle body..

Check engine light shows OBD-I code 33, and also code for MAP sensor. My question is, is 5AFE programmed to be compatible with EGR system? Even though I experienced better driveablity (awesome acceleration), should I go back to original vacuum system? Should I change the ECU?

I was using NGK G power plugs. The mechanic installed V-power double ground plugs. Wise move?

When I hit a speedbump slightly faster, there is a 'klung' type sound coming from the front wheel. What could be the problem- coil spring? or Shocks?

Also at Stop, or sluggish stop-n-go traffic, when I press the brake pedal, I hear sound coming from the bottom area inside cabin- not the brake pad, sounds like the line or something. what could go wrong?

Thanks guys