gas gauge is a ground problem in the tank where the pump sits in its bracket(metal) the fuel sloshes around and grounds out on bracket then gauge goes crazy. Simple fix use a zip strip to tie it away from the bracket and not starting probably in the tank again the pump has probably failed due to a dirty internal strainer(filter) on bottom of pump which gets dirty from rust and cloggs then it burns your fuel pimp out theyre made out of plastic gears. These spider injectors are testy they require 58-64 pounds per square inch of pressure and the poppets which are the little bearings or ***** at the end of plastic tubes will only open if your psi is over 58 psi once its running vacuum and vibration help open them. Gaurantee your pump is weak excellent fuel injection and get more power out of these spider injectors but fuel pressure and pump out put is a problem make sure the part store gives you a heavy duty high pressure pump these idiots will give a standard pump when the years only 2-2.5 yrs they put spider valves in the pumps from other blazers wont work they have lower psi dont let them *** you 94-95 s had spider injectors. Need pump that puts out 58-63 psi or wont work i went through hell to get my **** right i went to the better door store and got brand new hd pumps theyre puttin in new full size trucks they bought out from gm.also check the plug on the pump for wear where you plug the pump in the tank

 

My father S-10 (brazilian made, 2.4 liter engine) have a similar behavior and it was a bad hose (the fedding line to engine). Of course that thing cames pretty obvius if leakage is at a visible point, but if it at the tank could be different.

And do what swartlkk says, i had a "fuel pump" problem and instead to buy a 600 bucks fuel pump assembly (yeah, those things are pretty costly in Chile.. and that is the cost of Cartier Pump.. AcDelco is much costly!!!) I found out a melted pin and replace wiring even inside tank.

The misfiring code could come from out when you don't have enough fuel pressure, but it could be a clogged poppet valve.