Chugging at 50 to 60 mph

Hi, what do you mean by chugs at 48 mph ? Doesn't it go any faster then 48 mph, does it lose power, bog down when you press the gas pedal to the floor. Does it have a misfire , that makes the vehicle buck and jerk ! Is the check engine light on or any other lights for that matter ? How many miles are on this trailblazer ?

run the fault codes. check the serviceability of the cat converter as it may be broken inside and blocking the exhaust

Use a bottle of yellow HEET dry gas to remove any moisture problem in the fuel.

Check for coolant leak

Clean / replace air filter.

Check ATF at level ground. Top off ATF to MAX level.

Have to service these a lot it's the MAP sensor ( manifold absolute pressure sensor ) this should fixya.

Personally, the first place I would be checking is your air filter.

Have you checked the Angle Sensor

Check your Other Post....

plastic distributor ? wrong screws in rotor? timing?

Try swapping the fuel filter, it's a cheap fix and might just be the problem! Change the air filter also. good-day !

Deifintely have the converter checked. It may be partaily restricted and when seems to be working ok it may have dislodged a piece of the catalyst allow exhaust to flow freely again.

sounds like timing and tuning. or the carb is sticking