i have this dash light turn on when im driving its U/S and then like i let off the gas and it goes away then comes back on. is it serious?

 

I assume manual transmission?

The U/S light is merely a fuel economy light, it's saying for the best gas mileage, "UP/SHIFT".

You can do three things to turn that light off. First is to upshift into a higher gear. Second is to lay off the gas as you do, or third is to stomp harder on the gas. The light is merely a suggestion to help with your fuel consumption.

I don't think my 95.5(OBD1 with newer interior) had the light , but it was such a money pit that I never actually got to enjoy it, thus probably would never have noticed if I did.