I drive a 1990 Mazda 626 DX, 2.2 Liter, non-turbo.I recently got into my vehicle and heard a loud pop after starting my car, my engine quickly idled out and white smoke began creeping from underneath my hood. When I opened the hood, the white smoke was quickly dissipating with no visible source. I could not see any physical clues as to what may be wrong, so I tried to start my car again and check. Each time I start my car, the RPM's go up like normal and quickly idle out when going back down. I have checked my spark plugs, their wires and my air filter and all seem in good shape. Is there anything else I should check before taking it to an auto repair shop? Anything I can do myself before turning it over to them?