friends needs help not boosting proper

my friend has a 97 talon tsi with a serious boost problem .
when he gets up into the higher rpms (3500-4500 & 12-15 lbs boost) the car starts to surge.
it feels almost like when you bump start it but if i eez into the gas and keep the boost uner 10-12 lbs its ok .
he's changed all vac lines to make sure the are all good (no cracked lines) he also removed the mbc .
He's also done a boost leak test and fixed the leaks He also found out it also had the wrong plugs in it, changed that but nothing fixed this surge any suggestions guys as to whats causing this?

Sounds like fuel cut

Any mods?

its odd the car is all stock except for kn&n filter injen intake thats it

This is a fuel issue. Most likely the fuel pump is ready to die, or the wires going to pump assembly as damaged and the pump is getting low voltage at high rpm. I had the same problem on my Awd a few years back.

First thing should do is look into is a "fuel pump rewire." You can buy a kit for this.


Also pull the spark plugs and inspect then. They most likely need to be replaced as well if you are running a lean condition. Buy NGK BPR6ES plugs and gap them to 0.28"