I have a 1990 s10 blazer with the 4.3L v6. Ive recently started to experience major power loss and sputtering, mainly in first and second gear. Sometimes it runs great but other times i'll have to take it up to almost 40mph in second gear. It's extremely sluggish and jerks violently sometimes. I've replaced the o2 sensor, fuel pump, and the fuel filter. What can i do to get it running like new? Please help.

 

I would suspect you have a fuel delivery problem. Verify you have the correct fuel pressure at the TBI. (about 11 PSI is needed for a TBI engine). If pressure is low then you either have a fuel pump issue or a regulator issue. (The regulator is a spring and diagphram at the top rear of the TBI). If pressure is OK than I would suspect faulty injectors. A clogged injector is not going to throw a could but would explain the issues you are having. A cheap and inexpensive solution would be to throw in a can of Sea Foam in the gas tank and see if you get any improvement. (I believe the two injectors at the TBI run about $65 each at autozone.) A TBI rebuild kit includes a new spring and diaphram for the regulator. My gut feeling is that you have fuel injectors that are not spraying correctly.

 

Possibility of coolant getting into your oil....Check your cylinder heads for possible leaks...Also check all your vacuum lines for proper connections...

 

Thanks guys! I appreciate it.