Opel Vivaro 1.9 CDTI does not accept gas at intervals

Hello together, since yesterday I have a problem with my Vivaro, so far the car has run 19 years without problems and now a mistake is clouding my joy. I stopped before a traffic light with a slight incline, when I wanted to continue driving, the vehicle did not take any more gas, even several times try to press the accelerator quickly, remained without success. I h have towed me in the stand gas to the road edge and played about 2-3 minutes with the pedal, then briefly went a little the rotary fence l high, after that I could continue for 500 meters “normal”, from there (also another climb) everything went only with 10-20 km/h. After a short stop in a bus stop, I decided to drive the car about 8 km home and on the way I also noticed that for a short time (always when the error occurred) briefly the orange control lamp (preglamp) went on. On the last 4 km I did not notice the error anymore, my car drove as usual and also had power on the following climbs. Did anyone of you have such a mistake? Who can give me a helpful tip here? Thank you for your efforts!