97gmc Sierra keeps pushing it acts like it's running out f gas and engine code says multiple miss fires

A bad injector will cause a misfire. You need to replace it and see if the issue is corrected.

Go here to read the causes and solutions

A bad injector also shake the pcv and see if you hear it
you should have been had a check engine light with those will turn on check engine light how old is the fuel filter

Have you ever had the catalytic converter changed? sounds like its melted and restricting the exhaust from getting out of the engine.

I think you should buy repair manual first for your vehicle after that it will be easy for you to solve the problem. Check the link may be you will find something useful here
Chevy Silverado Sierra 1998 2006 Workshop Service repair manual

indicates injector problems and possible low fuel pressure
run the fault codes to check for EVAP and blocked cat converters

The P1320 code is essentially a coil primary voltage problem. This is traceable using a labscope or accurate DVOM and perhaps you can isolate one or two coils that still work but are close to failure...but there is a nissan service message recommending replacement of ALL coils with updated/improved models to prevent this type of failure. TCS/SLIP is traction control. Most likely you have a speed sensor issue. Be aware, some vehicles can falsely illuminate TCS because of low tire pressure in a single wheel.

P0300 indicates that there is multiple miss fire in the ignition system. P0303 and p0304 indicates the miss fire is in cylinder #3 and #4. Replace the spark plug, and wire set, and rotor and cap if there is one. Can not remember if there are coil packs on the civic, the age thing. change the fuel filter and clean out the fuel injectors with fuel injector cleaner for the next 3 full ups. When the spark plugs are removed, inspect them for condition, if there clean or dirty with carbon build up. which would indicate how the engine is running. Keep me posted and drive safe.

Have you put new sparks plugs in it. If you havent I would try them first. Only run the ac delco plugs listed for the truck. I have had many people come threw the shop with misfiring and trucks running like **** and come to find out they put bosch or ngk plugs in it. Your manual says there good for 100,000 miles but there really only good for about 75,000 or so. Also run some lucas fuel treatment or b12 chemtool. both you ad straight to the gas tank. If it calls for one can for 20 gallons buy two and double the treatment it wont hurt you engine.

sounds like a eng miss fire eng lite on OBD 2 scaner tool to retreve code don't GUE$$ the problem