2004 TDI PD Jetta - Over the past several months there has been an occasional cylinder misfire when the engine has been cruising for about 1 hr. It is unpredictable short lived and then runs fine. In the last few days it has become more noticeable and once the engine is warm it the hesitation starts and continues as if the injector failed in one cylinder. If I turn off the engine and immediately restart it then the problem goes away. Any ideas?