I have a 2001 mercury cougar, everytime the fuel gets to a half tank or below it stalls when going up a hill or around a curve, anytime u give it extra acceleration when it’s a half tank or below it stalls and sputters, it’s been in the shop for 3 months and got it out and ran good for a day now back bad I need a machanics advice on what it could be other than fuel pump, fuel filter, o2 sensor, or plugs and wires… I’ve tried all of them
Sounds like a fuel problem. Connect a fuel pressure gauge to the rail.
An O2 sensor will not cause stalling.
Plugs and wired will not cause stalling on a 1/2 tank. Worn plugs and wires will cause misfiring.