'90 civic / no start and/or fast rpm's

When I start it cold there has never been a problem. However
about 1 start out of every 4 or 5 when it is already warm one
of 2 things will happen. 1) it will struggle to keep running
right after it starts for about 2-3 seconds then the engine will
"race" (the rpm's will shoot up to right around 2000 and stay
there. When you put it in gear you better be ready because
it is going so fast you have to hold it back. Even if you turn
it off and start it again the same thing will occur. Sometimes
the rpm's will even "surge" from 1500 or so to 2000. -or- 2) it
won't start probably for about 2 minutes. It cranks and cranks
like it is flooded and so far I have always been able to get it
started but the last 2 times the battery is starting to get a
little slow/weak before it will finally start.

After it starts (if it is not "racing") it runs great. It does not
appear to have any issues after it has been running for 5 or
more seconds.

The last couple tanks the fuel milage has also decreased by
3 ro 4 m.p.g.

Any ideas/advise/suggestions would be helpful. Thanks.