1998 Jimmy. Will crank but only for a moment then goes dead again. I smell gas pretty strong. I have replaced the fuel filter

Sounds like a couple issues possible. If its cranking the battery is good and starter (but double check the battery because it shouldnt die so quickly). Also heres my theory since I am not physically there to confirm. If the battery and starter checks out fine, you may be getting and over excess of too much fuel into the cylinder and its causing piston lock. Possibly from a bad injector(s) or no spark to ignite the fuel that's coming into the cylinder causing it to collect there as opposed to burn and start the motor. Basically too much fluid in the cylinder then the piston can compress and it just causes more tension then the starter is designed to turn. This will still need to be checked by a mechanic but you can prob check to make sure there is spark in each of the cylinders. Go to Harbor Freight and buy this $5 tool to put on each cylinder and see if you have spark if not you have an ignition issue, if you have spark I would start looking at injectors. You will need a mechanic with injector tester machine to test pulse/width durations... Here is the link and hope this helps.
http://www.harborfreight.com/catalogsearch/result?q=spark+plug+tester