2000 blazer with 140000. eveything else works and feels fine, just acceleration is horrible...just put in some seafoam, new air filter. Got any ideas or has anyone had the same issue?

 

Try reving the engine in neutral. If it won't rev up, perhaps the catalytic converter is plugged. Does the converter rattle? Sure sign of failure.

 

mine did the same thing . going on the highway at 70 hit a hill slow down to about 30mph . got a new catalytic converter now runs like a champ!

 

Newbe question so it may be dumb, but how does the catalytic converter effect accelleration? I have the same problem. I'll check for both tonight when I get home. Thanks.

 

It restricts the exaust gases,an engine that cant breathe in and out wont work well.

 

i have the same problem but it runs fine if not in drive,only when driving.i was told to unplug the mass airflow censer and it cleared up but that is not the problem.any ideas??

 

The only way a catalytic converter will adversely affect acceleration is if it is restricted (i.e. plugged up). A properly functioning catalytic converter will have very minimal affects on the operation of the engine.

As far as the poor acceleration problem... When was the last time that a full tune up was performed (plugs, wires, cap, and rotor)? How about a good cleaning of the EGR valve, throttle body, and/or MAF sensor?