My TCS (check engine) light remains on. The car has an uneven idle when parked (sometimes). The DTC code is 86 (Exhaust Gas Recirculation - Insufficient Air flow to EGR). I changes the intake manifold gasket and cleaned the EGR valve. The problem is less, but still persist, esp when engine is hot. Normally, when in park the engine revves up and down for about 3 or 5 times and then goes into a normal idle. Also the check engine began to blink suddenly while I was on the highway going uphill and I tried to shift from D4 to D3. Please help me diagnose the problem? The honda dealers can't pinpoint the problem and just said it might need changing lots of parts. That is not very assuring, since they have already charged me $500 and still not successfully diagnosed the problem (that is causing the check engine light to remain on).

Noor