Scenic starting problems

I have a Scenic 1998 with an infrared key. About 1 month ago we had to change the coils so the car was going no problem. About a week ago the car started to struggle firing after a short trip, then few days ago left me in the street as it stopped while running and could not get it firing again. Fuel pump goes ok I can hear it, immobilizer OK as the key turns it on and off no problem, we checked the power, everywhere power excepting on injectors and to the plugs (there is power only for few seconds on them as well) same as the immobilizer would do, although the light shows its working correctly. Does anyone have any idea what it could be? I also looked on the sensor attached with two bolts on left side of engine, was clean without any problems. If anyone knows what to check further or any idea of what it could be, let me know, thank you.In other words the immobilizer light shows that tthe immobilizer is OFF but the power cut after few seconds to the injectors and coils is like it is ON. Thank you.