I have a 99 Honda Accord and I have noticed a couple things happening:

-when starting up the car it will sometimes struggle to start. It has always started, but sounds off (sorry, that is super unspecific).
-when I stop at a stop light and idle in drive my car will be vibrating slightly.
-Again, when stopped in drive, my car will "chug." I haven't noticed a variance in rpms except maybe a needle wiggle, but it sounds and feels like the car is losing power and then recovers. This doesn't happen when idling in park.
-when accelerating out of a stop, the chugging will continue as I get up to speed. It feels like the car is struggling to change gears or get power.

It has not stalled on me, but just isn't quite right. Could this be a vacuum leak problem?

I'd welcome your input!

 

It could be a vacuum leak problem, but it could be a lot of other things too.
You'll get better guesses if you can provide a little bit more info.
Is it a V6 or 4 cylinder?
Do you have a check engine light?
If you have a check engine light find out what the error codes are.

My son's V6 had a similar problem and no CEL. Then I found out that the bulb for his CEL was burned out. It turned out to be 2 problems which are common: The EGR port was clogged and the front O2 sensor was bad.

 

It is a 4cyl and there is no CEL.

 

check your distributor cap and rotor. you could be miss firing slightly. depends on how often it happens that it will set the cel. pull the cap off and see if its corroded on the contacts. also make sure your getting good spark and check spark plug gaps.

when was the last time you did a tune up?