Monte won't accelerate missing on all cyl. put my hand over exhaust pipe very little pressure can block it off easy. Plugged cat right?

 

Take it for a hard run and you should see it glow red if it's plugged bad...

 

That would be my guess to.No exhaust something is clogged up.When I was little my dad had a car that the catalytic converter was clogged up on and something underneath the car caught on fire.(us kids were in the car)So the first thing I do when I get a new car now is cut that thing off!LOL

 

Plugged Catalytic converters are common...

If the exhaust cant get out of the system nits going to fall on it face and spit and sputter... Is there a CEL? (Check engine light)

 

Did you do any work to the car (like changing plugs/wires) prior to this problem arising? Has the car sat for any amount of time? If you suspect the cat you can remove the front O2 temporarily and see if the engine runs better. If you can make it to a shop they can conduct a test to determine if there is any blockage in the exhaust system.

 

my 02 did the same thing, unplug the map sensor and see if problem still appears...if it doesn't replace the map sensor...had the same prob. and it fixed it with new sensor. (side note) if you can start it run it a bit hard...look under car and see if cat is glowing red or the U-Joint infront of the cat. After that tst, plug the map sensor back up and unplug the MAF sensor and see if that doesn't make all the problems listed go away, if so replace the MAF sensor $80 dollars is better the 300$ for the cat and it not be the problem , both test are easy to do