My 1992 blazer S-10 tahoe, 4.3 vortec, 4wd ran awesome when I bought it a week ago. The gauges were burnt out so I had no idea how much gas was in it. After 2 days of nasty snowstorms driving very slow in 4wd constantly, it started running very rough, like it was running out of gas, bucking and skipping.
Thinking it maybe was out of gas, I replaced the fuel filter and put in 6 gallons of mid-grade gas and an expensive bottle of fuel system cleaner, still ran rough.I replaced the gauges right after that, the fuel gauge showed barely any gas in it (with 6 gallons of fresh gas in it), so I put in another $30, and now gauge shows 3/4 tank, still running rough.
It starts right up as soon as you turn the key and idles smoothly and consistently, but it did die once during idling (only 1 time). It's when you press on the accelerator that you notice it, it's like it's holding back, like theres water in the gas, or not enough spark. When in Park, if I goose it and rev it up, after about 3 big revs, it "cleans out" and will redline with no restrictions. When driving it, at times it will run awesome, and will go into passing gear nicely and do 80mph no problem, but then when I slow down and try again, it will run doggy, like gas flow is restrictedand a couple times died. When it dies, it doesn't want to start but wil after some turning over.
I replaced the plugs, wires, cap, rotor, fuel filter, and air filter, it made no difference at all.

Would running it out of gas cause this problem? Or could there be a ton of water in my gas? I don't know what to do next other than take it to a qualified mechanic.
Any suggestions would be immensely appreciated!

 

Bump for similar conditions.....

 

Possibly a failing pump, or a bad throttle position sensor. Check fuel pressure, and use an ohm meter on the TPS.

 

Well playing around w/ the truck yesterday, I HOPE I got it figured out. I started pulling vaccum lines one by one and making sure they weren't blocked and didn't have holes. I cleaned the MAP sensor by spraying a little carb cleaner inside of it, thenblowing air inside of it to clean out any debris. CEL came on as I was pulling hoses while the truck was running, lot of idle changes One thing I got to start working which I don't remember ever seeing doin anything before is the flapper valve in the intake tube. It diverts the air coming from the front of the truck to the heatertube above the header collector for cold starts. Odd thing is the motor was fully heated and the flapper insisted on being open, diverting the heat from the header. I played with the little green Temp Sensor that sits about 10 o'clock to the air filter, and I noticed that when I pushed it's tiny little plunger down, the flapper in the intake tube would close allowing air to come from the front of the truck. After playing withthe sensorfor a little while, it must have freed itself up or something because it was finally staying open and sucking air from the front. I have yet to start the truck this morning, but i hope it drives as well as it was yesterday....felt "right" once again after playing around and pulling/clearing tubes yesterday. Wish me luck.[/align]