1993 Chevy S-10 poor mileage and can smell gas

Try cleaning the throttle plates with choke cleaner as it may be gummming up. Also if you are smelling gas check your whole fuel links for leaks. It may be some slight leakage on the rubber hoses, but shold be looked at. The shudderig may be due to the throttle plate sticking. But also change your fuel fileter as it probably never has been changed. If your check engine light is on have your system scanned for codes as well. Due to this being a pickup you may be leaking fuel from under the bed as one of the fuel lines or rubeer lines going to the tank may be leaking.