97 nissan sentra acts like its getting no gas

It's so difficult to guess without being able to experience the problem first hand and at least do some basic diagnostic test. Has the check engine light been on? Your car has On Board Diagnostics (OBD2). A 16 pin diagnostic socket under the dash allows a scan tool to be attached to interrogate the on board computer in your car. A professional grade scan tool reads stored trouble codes,pending trouble codes, looks at live sensor data so you can look at a sensors performance and output signals without having to do intensive testing at each sensor, (cheaper scan tools have limited capabilities and may only read the trouble code stored). As with most things automotive its best to check the basics first, check for vacuum leaks, fuel pressure and delivery volume. Verify engine mechanical integrity before looking for complex problems check that the basics are sound. With your car verifying fuel pressure, checking for vacuum leaks and the air flow meter values would be important to check.