ive got a misfire up to 3000rpm, after that is seems to disappear but the car is down on power revving a lot slower than it should, so far i have changed:

Both lambdas
Fuel filter
All 6 injectors
The fuel rail
Sparkplugs
coilpack
ignition leads

ran my obd scanner and got some codes

p0401 (Exhaust Gas Recirculation "A" Flow Insufficient Detected), expected as ive removed the egr
p1131
p1151 (running lean)
p0171 (running lean)

apparently running lean could be a fuel pump issue or fuel pressure?


regarding fuel pressure, i bought something a while ago, can i use this to test the pressure if i remove the schrader valve and pop a hose, would that work ok?



engine is a duratec v6, really hoping someone can help.