I have a 1999 infiniti i30 with 110000 miles, very similar to a nissan maxima. Recently I had the valve cover gasket changed, since then there is a rough idle when I stop and in drive or reverse gears. It is a little better in nuetral but the car starts shaking back and forth after some a few seconds. The car drives smooth, if I give some gas, the shaking goes away, if I don't the rpm keeps droping and when it reaches around 500 rpm and starts shaking. The mechanic who changed the valve cover gasket, cleaned the throttle body, EGR value, but no luck. When he hooked up the scanner to scan for codes, it didn't show up any codes.
so no idea what the problem is or how to find what the problem is?