97 GSX Sudden Drop in RPM

[timetoski]

I Recently purchased a 97 GSX. When cruising at around 5500 RPM the revs will suddenly drop 500 with no change in throttle and after a few seconds jump back up again. Is this possibly caused by RAVEs sticking or more likely fuel issue. At full throtlle it is steady - no drops

 

[Dr Honda]

Probably just the RAVE's.

I won't rule out a fuel issue... but when the RPM's drop... can you open the throttle, and still have a good response?

 

[timetoski]

Throttle is still responsive

When I open the throttle after the RPM drop I get a good response.
So what happens is that if I start off cruising at 5500, and then RPM suddenly drops to 5000, I can quickly bring it back to 5500 with throttle but then a few seconds later the RPM will jump up again to around 6000.
Thanks for the help!