misfire. wont pass inspection.

[Ortiz512]

hi im new to this site, i recently bought a 94 chevy astro van v6 4.3l TBI . took it to get inspected and they told me it failed the emission test. on low rpms. . do to misfire. I took it to O'reillys to get it scan, but no codes came up. since then i been trying to fix the problem myself,(not a mechanic). so i stared replacing the fuel filter, fuel pump,spark plugs,wires,distributor & rotor,IAC,EGR,ignition coil,and fuel pressure regulator. took it back to get re-inspected and fail again. but this time also on high rpms. the van starts good, oil pressure goes to 40. then i slam on gas and it acts like it wants to die, or choke the oil pressure drops to 20 and then after a few seconds it picks up. once warm the oil pressure drops to 20 on idle. sometimes it seems as water coming out the exust pipe, and it smells rich on fuel. at this piont i dont know what else to do.

[chevymaher]

Lucas fuel injector cleaner in case the injectors gummed up.

[Ortiz512]

Thanks I'll try that.

[paintdrying]

You could always take to a real mechanic and have them use their scanner on it. Have you changed the oil, was the engine hot before the test
? Those base gaskets at the tbi tend to leak. And Lucus cleaner as well, before the oil change.. What state are you in?

[ihatemybike]

I had a persistent misfire with Grumpy. Ended up being the cam-shaft sensor.

[Ortiz512]

Yea I did change the oil and the engine was hot when tested .I live in austin,Texas. I'm having a mechanic check it this weekend. Fingers crossed it's something small.