why does my 1992 honda civic DX 1.5l act like it's out of gas around a quarter tank

What are the symptoms when it acts up?

it chug's like it's out of gas but i can still drive it like that for mile's but not over like 30mph

When you say "chugs" do you mean the engine is skipping? When an engine skips, it feels like you just drove through a small patch of glue, then the car suddenly regains speed, then repeats over and over. Is your check engine light on?

yes it is now

the engine like go's up and down in rpm

Buy some throttle body cleaner and clean your throttle body. Remove your Idle Air Control valve and either replace it or clean it. Here is a short video: https://www.youtube.com/watch?v=tUkCCwqU3eU If car runs good enough to after cleaning, go to Autozone and have them read the error codes for your check engine light. Write them down and post them here. Car may run fine after the cleaning. Also spray some cleaner into your EGR. That may be plugged also.