Engine/Transmission (1998.5 - 2002) boost problems

[BMorse]

If anyone can help. I installed a suuperchip in my 99 and now it wants to lose boost at about 75 or 80 mph. I have 4 inch exhaust and a K@N air filter. can email at -- email address removed --

 

[DCreed]

do you have a fuel pressure guage yet? may be running out of fuel on the top end.