Sudden droppage of RPM's and Throttle surges

[Kenley Meza]

Hey guys whats up well my SR20DE-Tized engine is fine
so far except that I added another fan from another
car and when I'm idling and the fan turns on, I can
tell cause it's pretty loud, the car starts to have an
erractic idle from 450rpm to maybe 750, if you guys
know what is going on please help me, also when I
barely press the throttle it kind of surges but only
when I'm barely pressing the throttle, do you guys
think its the fuel pump, cause my friend in his B16
crx does the same thing??he also suspects his fuel
pump?

please any help would be grateful, I've checked the
archives but no luck, if you know let me know:) thanks

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1992 Sentra SE-R with K&N Intake and 5ZIGEN exhaust (mandrel bent)
Only a Downpipe away from boosting a T25 oh yeah and waiting until JWT returns my ECU....