Rpm Raises Between Shifts

[SN95BOSS]

Alright just bought my first stang and seems to have a minor problem, maybe a vacume leak but can't find anything? While shifting gears when you depress the clutch the RPM's raise by about 500 RPM's in between gears until the clutch is re-engaged (will drop eventually but takes at least 5 sec if you keep the clutch depressed). Also RPM's take awhile to drop to idle when clutch is pushed in rolling to a stop, for about 5 seconds tach will sit at 1500 RPM then finally drop to idle speed or just reving the motor in nuetral gives the same results? This seems to be a intermitant problem but happens more times than not with no particular pattern? Any suggestions on what to check? I have always done most of my engine work myself but dealing with imports (please no remiders of how stupid that was/is), finally realized where real power is made

• 95 Mustang Boss
• stock motor with cold air intake
• 3.73's in rear
• off road H pipe - no cats