hello all I have a 94 s10 blazer tahoe with the 4.3 vortec that is the biggest pain in the a-- most of the time it will not start. When it does start and run every time i drive it it starts to spit and sputter and shake and stall out around 35 to 55 mph. The check engine light does not come on and it dosen't read any codes and it don't blow any smoke. I have replaced the fuel pump, sending unit, fuel filter, cap plugs and wires, and the computer and nothing helped. Ive been told it could be the fuel flow sensor or a controll module but it don't show any symptoms of thatDoes anybody have ideas of what the problem could be? I really dont want to have to junk it or part it out cause its a great truck yet so any help would be great.

 

OK, deep breath, relax. The basics of the internal combustion engine = FAST. Fuel, Air, Spark, Timing. Without any one of these things, the engine will mis-behave. Of course, modern engines have all the extra crap (computer, sensors, etc) that play in, but the basics are the basics. If you can eliminate all the basics, then you have to consider the crap.
A long time ago, my Dodge Caravan mis-behaved suddenly, similar to what you describe, spit and sputtered, lack of power,etc....Unfortunately I was 50 miles from home, at night, towing a camper and the whole family (3 little kids then) on board. Thankfully, I managed to limp all the way home (on the highway no less). Took it to the dealer..diagnosis..3 sensors BAD simultaneously. If memory serves correctly..throttle position sensor, idle air control, engine speed sensor (or some such beast). Replaced all three and we were back in business, good as new. Squeeked in just under the 100,000 warranty too. Lucky me.

PS: I don't think the CEL went on either.