Chevrolet Repair: 01 4.3 Blazer MAF/Multiple Misfires, vacuum line, vaf

Question
We have an '01 4.3 Blazer.  It starts and idles fine.  When you accelerate to 2500 rpm's, the engine bogs down, stumbles and almost dies.  If you take you foot off the pedal, it will  recover after a minute or two.  We put a reader on it and it said MAF/VAF and mutiple misfires.  We have replaced the following and nothing has changed: MAF sensor, fuel filter, MAP sensor, coil, the module that's next to the coil (ECM?), distibutor cap and plugs.  Any ideas? Thanks.

Answer
Obviously you did NOT do any of the required test procedures BEFORE you started replacing parts. At this point you do NOT know if any of the parts that you have already replaced are working at 100% efficiency or NOT.

I would start with a BACK PRESSURE test on the exhaust system looking for a partially restricted catalytic converter.


What mechanical work or ANY kind of work has been performed on the vehicle recently ?. As most problems that occur after a recent repair was made can be traced back to the area of where the repair was made as a vacuum line may have been knocked loose or a wire connection came loose, Look around in the area where work was performed..


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