FC bounce idle
 

I have an 88 FC Rx7, I'm still fairly new to rotary engines. I do have basic knowledge of them. When my FC warms up to operating temp. it seems to bounce idle or rev slightly. I can rev and drive the car just fine.

I bounced at idle as well with a t2 I just got. I found a vacuum hose leak and my turbo inlet duct had a crack, which is basically more leak. After I took care of those, my idle was much smoother.

Usually any idle problem, 95% of the time is a vacuum leak

Just to clarify, what is a bounce at idle? Once warm my car goes from around 800rpm to 750rpm, it just kind of dips down by 50rpm for a second then goes back up.
The car pulls to redline in gear just fine like the op. If I check all my vacuum lines I should expect to find a leak? Is there a good trick to finding very small leaks such as spraying with soapy water or is that bad for the rubber hoses?