90 Cougar stalling and knocking
 

About a year ago I had some bad gas, then had fuel filter replaced and did an injector treatment. Stalling a couple times a month max, figured I could deal with it. Lately it's happening more often, and there's a knocking/stuttering (noise comes from rear passenger seat area).
If this was a fuel pump issue, wouldn't the pump just completely stop working?
Should I clean out the throttle body? Any suggestions? Thanks!