So I have a 2000 Chevy Blazer LT 4.3L with 160,000. I have already replaced the MAF Sensor as my dad has the exact same truck just 2 years older and 10k less mileage and had the same acceleration issues. Well acceleration has been fixed but the truck shifts REALLY hard from first into second if you floor it.....i already know it is NOT the transmission because the transmission is in great condition. I have also noticed that when it does this the tires jump. So its not having an issue with shifting. My dad had given the suggestion that it is the vacuum actuator.......that is the only gear it shifts hard into. Anyone else had this issue before?

 

So i read the vacuum actuator has to do with the 4X4......i have no issues with the 4x4. I have an Auto 4x4 Switch on my dash that i dont quite get to concept of because if that is on it seems to ALWAYS have the 4x4 on no matter what. But I have seen some people mention something else to do with the TCC....i have no SES light on, but i know that no SES light doesnt always mean there are no codes that will show up. Just means the code may or may not trigger the SES light. I am going to take it to the auto parts store and see if i can pull any codes. If anyone has any other ideas please let me know so i dont spend TOO much money.

 

accumulator or 1-2 shift sensor in the trans