For starters - after looking through the forums - I hope that I am posting this to the right spot.

I have a 2014 Audi A7 3.0 TDI - the following has been happening.

Late summer last year, I would start the car and the RPM would start dipping down and then shooting back up. This was accompanied by flashing glow plug light. I was able to pull away with no issues while driving, the occasional dipping again while idling at red lights, and once the dipping causing a complete stall.

After a few days of powering through it, the check engine light came on:
P008700 - Fuel Rail/System Pressure - Too Low
P053F00 - Cold Start Fuel Pressure Performance
O204B00 - Reductant Pressure Sensor Circuit Range/Performance

We would clear codes - stopping all issues - then it would come back after a few more days of driving. We checked for metal and found none. We then replaced sensors, fuel filter, and added injector cleaner. None of these added an immediate fix - HOWEVER - once the cold weather hit - I drove without any issues or lights for about 5 months. I started only getting fuel from one high turnover spot and chalked the issues up to bad fuel.

The issues have now started again (the weather is back to the summer heat) - with the flashing glow plug light coming on one day while cruising at 60 mph. This eventually turned into check engine light and dipping RPM at idle.

Any thoughts or suggestions would help tremendously. I appreciate it in advance.

 

**UPDATE**
Drove the car today with the check engine light on.

I accelerated onto the freeway rather hard. Once I hit 65-ish mph, I lost some power in the car and the glow plug light began flashing again. I was able to get up to 80 mph but it was with less power than normal - while still going through the gears as normal. One piece that I noticed was that my cruise control did not work.

I reached my destination - and had the car off for about 3 hours. I started it up and it drove home with full power - no flashing glow plug light - and cruise control working again. I did refrain from hard accelerating up to 80mph and used a more gradual approach.

 

That's a strange one. Any codes this last go around?