I am not familiar with the engine of your car, but in my case before nung medyo bumabagsak yung idle (esp. during braking) nde lang maayos yung adjustment ng valve tappets. Kung may Idle air control valve (IACV) yan pacheck mo na rin.

Parang medyo mahal rin yata inabot at ang daming pinalitan... presyong engine swap na halos...