why when driving at 60 to 70 does engine start to loose speed and stall on 2003 BMW 325i

problem of car stalling and now this power loss after having work done to the tune of over $1900.00 never had this before they replaced, intake sensor,exhaust sensor,front brake sensor,control arm bushing,205/55/16 something???/regulator and more, all so engine light would go off and pass inspection. this car never stalled out and never ever lost power as it was being driven at a speed over 65 . this is the 3rd time since this repair i have had to bring this auto back. i am out of money so i can't even bring it to a bmw dealer, which i should have done to start with. help! what are my options?????????????

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2 answers
Could be any number of things mass air flow sensor, low fuel pressure, restricted catalyst . You need to bring to a shop that has expertise with your BMW like Jensen's Service
Had 2 diagnosed 1 at BMW dealer.
O2 sensors changed, thermostat, idle control valve, new air filter with filter pad, mass air flow sensor . Still all warning lights come on and runs rough, gas mileage drops off bad, wants to stall.
Sometimes after 20 miles other after 2 miles. 4 months of trouble. Please help