I purchased a 2001 blazer 4x4 in March of this year. It had a whining fuel pump when I bought it, but tested it and there's no loss of fuel pressure, it's just noisy.
Fast forward to the end of June. Taking the kids to buy school supplies, stopped and filled up the tank. Drove for 5 miles, hit minor bump (the equivalent of hitting a squirrel), and lost all acceleration. Pulled off the road, tried to drive, but no acceleration. Called the lot I bought it from and they came and towed me in. Couldn't find anything wrong.
This happened multiple times, always kicking itself off at about 3500 rpm....usually as it's prepping to shift at about 45mph.
Everything was looked at again and still nothing. At the shop 5x, they finally cleaned my mass air flow sensor. That worked for 2 days before it started again. Gas mileage is ridiculous at this point, less than 10mpg, but still showing no loss of fuel pressure. Replaced the MAFs
Friend of mine comes to look at it and realizes they used the wrong one, so I ordered the correct one and drove around with the other unhooked while I waited.
new part put on, still lost all acceleration at 50mph, and now any time It does it, my service 4wd light comes on. If I put the truck IN 4x4hi and drive it, it drives better, and no loss of power. Of course that still means I can't go anywhere outside of town where the speeds increase.
No one can seem to figure out what's going on. My kids go to school on the other side of the county, so if they get sick or something happens at school, I'll have no way of getting to them. Anyone have any ideas?!?!

NO SERVICE ENGINE LIGHT IS ON (OTHER THAN WHEN THE SENSOR WAS UNPLUGGED)

ABS AND E-BRAKE LIGHT CAME ON INTERMITTANTLY AFTER OURCHASE, BUT HAVE STAYED ON SINCE THESE ISSUES STARTED. BUT CAN FIND NO ISSUES WITH THE BRAKES.

SERVICE 4WD LIGHT COMES ON WHEN ACCELERATION IS LOST.

 

Are there any codes?

How did it drive with the MAF sensor disconnected?

Did you perform the fuel pressure test in the sticky at the top of this forum? The leakdown is important.

George

 

Engine light code was for the air flow sensor. I drove it for a week with it unhooked and it ran better than before, until the last two days when it was running rough. It still lost power though :/
I haven't read the sticky note yet, but the shop put a gauge on it to read the fuel pressure as they drove it around and it never dropped.

 

Have you hooked up a scanner to see of there are any codes or pending codes?

The fuel pressure test checks for more things than just pressure during driving. It also checks for leakdown. What pressure level di the shop read during driving?

George