Skoda Cutting off while idling and not accelerating

Hi There, My Fabia 2003 model has been down for two weeks. All diagostic tests are negative after changing accerelator pedal and checking plugs, fuel pump everything. However, car is still not accelerating at certain intervals and continuously cutting off in traffic (when idling). The engine will restart and car will drive perfect above 50 mph. Please help me someboby!!!:(

Ignition switch or engine ECU relay would be the two prime suspects, nether leaves a code and both are common problems.

Thanks Crash! I will let my mechanic check it out. :beerchug: