While driving around 50-55 mph the engine has a miss, and sometimes while idleing. I already tried fuel treatment and new plugs,oil changing. The engine does not loose any water or use any oil. Where should I start looking.:eek:

Clean your Idle Air Control Valve/hoses, ports, and throttle body. Even though the link below is for Hondas, it offers some guidance:

https://www.askmehelpdesk.com/cars-t...ml#post1054149

I'd start with EGR. Pull it off and test it with a vacuum pump. Make sure it's not sticking.
Clean the ports of any carbon on the valve and the intake plenum.
Also, the cold start injector on these bleed down and cause rich start ups and idling.