508 Sw with Random Stalling at Idle.

Hi, for about the last 12-15 Months my 508 Sw has had a weird issue, intermittent stalling when stopping at traffic light the rev counter gives a small blip and then the engine just dies. No faults are showed on the display no warning lights etc., Car restarts first turn of the key and stalls again unless I give it some revs above 1000rpm, idle does sit at 900 cold or about 750 hot. It is totally random when it will do it, but if it does it once it will do it 4 or 5 times, restart fine on the key. just Weird, I have had a full service done inc fuel filter still does it. The car is a 2012 508 Sw Active 2.0 Hdi. My Vin is VF38ERHF8CL033315

I have bought the download tool with pp2000/diagbox checked. couple of codes store. Maybe some one can explain the last one.

B1825: Oil level information fault. Level too low (now top up to max mark on dip stick was in-between min and max)
B1418: Fault in status of seat belt fastening information for determining the presence of the driver. (I was now wearing the seat belt at the time)
B1816: Fault loss of the hybrid drive train status information (Then again its not a hybrid)

U1F00: Fault event not stored in the fault log.

I cleared 4 codes which where in it. Changed the filters and starting using BP ultimate Diesel and it was fine for a while. You could still see the revs drop every now and again but the computer would catch it. but this morning it stalled about 6 times in a row. the only code stored is in the BSI module code is B162C 12 Fault Accessories Positive Relay Control & Status not coherent. If you clear it and retest (with out starting the engine ) code stays cleared same with starting and stopping the engine on the key. but if you let it stall/cut out the same error code appears again.

After doing some google research, I came across some C5 owners (same engine) who were having stalling issues, like mine no engine management lights/weird error codes etc..Mines only had (BSI or body system codes apart from the U1F00 code still don't know what that is) Turned out for some of them, the air control units were dirty (also called by some sites and you tube the throttle body), So I stripped mine off, really easy 2 electrical connection, two T30 screws one T30 that you don't take right out and disconnect the air duct and a small vacuum tube. Inside my air control unit was very dirty. thickly coated in oil and dirt/carbon from the EGR and Breather tubes. The Air Temp Sensor you could not even see due to the Grime. So I cleaned everything out and reassembled. Used the Peugeot Planet tool to reset everything and did the actuator tests etc.. Car is running fine at the moment but only time will tell..

I did notice when its at idle every 30 secs or so you can hear and feel the air flap open and close does this exactly 5 times in a row like open close wait a sec open close wait a sec 5 times then idles perfect for approx. 30 secs then does the 5 open close cycle again. suspect this is the EGR Valve

Left the car at idle for about 30 with the Peugeot planet connect. No issues.

guess what still stalling. Unplugged each sensor on the air side from maf right up to air pressure sensor one at a time. Each one gave a P???? error code and made no difference. so cleared codes, unplugged EGR valve plug again no difference. and again cleared the codes. HELP...

Regards
Ed.