will not idle .periodic backfiring ,no power
 

Hey everybody . 1993 g20 100,000 miles 350 , sudden stalling, misfiring ,chugging and backfiring , almost did not make it home 30 miles at 25 mph then 15 last few miles . I found original plugs wires cap rotor were original and I replaced . had ecm tested once and found ok the other kid at oriely said it needs to be tested 3or 4 times to heat it up . I have reasonable spray pattern at both tbi injectors going to check fuel pressure soon had changed filter and verified fuel pump is running . I am getting a code 13 throttle positioning sensor or oxygen sensor ? pick up coil tested fair with my limited diagnostic skills . also replaced coil I am buying the borg warner stuff or what I believe to be the better parts at oriely . Its an old chevy it should not be this hard . currently if I prime it a little and pump gas it will half ass run but not idle on its own . it may backfire and start fire at top of tbi please help this is my big family grocery getter

Just so I have the time table correct.... You tuned it up after the engine started fussin', correct? If that's the case, I'd say it's a fuel pressure issue imo. Checking the fuel pressure on the tbi engines are a pain since they have no test port. The back fire through the tbi would indicate that you either have the ignition timing off, or a lean mixture..... I'd chase the lean mixture. Fuel pump going bad or the fuel pressure regulator going bad. There are a couple of tbi fuel line adapters with a test port in them. One that mounts to the tb where the fuel line come in, and one that take the place of the fuel filter. Makes checking pressure super easy.