1999 e300 TD stalling on Highway and Town

[Miraboy]

I am 3rd owner of a 140km e300TD , also own an 87 e300td 175Km, (great all round car) bought the 1999 in summer 2012 , a garage stored car, never winter driven (means a lot here in Nova Scotia). Car worked perfectly last summer , stored for winter. This spring can began stalling while driving, check engine code P1622, replaced the fuel shut off valve and O ring, wire harness was OK, all fuel lines were replaced with new O rings, no leaks no bubbles, stalling continued every 125km or so. Replaced the K40 and fuel pump relay, battery is good, all wiring connectors appear to be OK.... Beautiful car but I am on a short leash, I am new to this organization and after reading so many good technical posts I thought someone may have experienced this stalling issue and found the solution? Very nerve racking when car quits and dash lights up at highway speed, Thanks
Best from Halifax