Loosing boost thinking vaccum leak.?

[suitercrew]

Hey guys currently ive been having some problems it started off as my mpg went from 17 to about 14 for no apparent reason. I did get a check engine light for the upstream o2 sensor having a slow response but then the light went out on its own. While i was trying to figure out the bad mpg problem i started notice some occasional idle surges by about 500rpm while in park and also i was putting out about 6.5lbs of boost with my top swap on a stock pulley and when i tested it right now via torque pro i peaked at 5. Any thoughts?

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[SgtMarshal]

check your LTFT's, if you have a vacuum leak, they will be highly positive like 16.4

[Turbocharged400sbc]

Change the Upstream oxygen sensor

[suitercrew]

Change the Upstream oxygen sensor

Could the o2 sensor be causing my low boost? I checked all my vac lines and there all new and none are leaking some im confused

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[suitercrew]

Like 16.4 at idle? Cause i tuned my fuel trims and they lock in pretty on point

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[suitercrew]

Status update i was logging some data using torque pro and noticed im now getting 3 degrees of kr when before i had none. And also my fuel trims are both locking in at 0 as if they have not learned yet although i have not reset my trims or taken out the battery anytime recently

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[suitercrew]

Anything guys?

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[Fivefingerdeathpunch]

Nope.