My 2000 blazer is missing or stumbling. Sometimes not bad other real bad. The cat is finished could this be my problem?

 

possibly, but I wouldn't jump straight to the cat being the root cause. when's the last time you had a basic tune up? if you can't remember or it's been a LONG time, I'd try cap/rotor, plugs, wires, PCV valve, fuel filter, air filter, could just be something simple.

is it only at idle? on acceleration? cruising speed?

 

I did a tune up about a year and a half ago. the problem is on acceleration and a bit at cruising speed. I did have misfire code I switch the coil wire witch was arcing to the coil bracket. it was working better and this moring got bad. The only code I have is a 440 code. I still have the old wires witch I think are still good,I plan to change them tonight after work.

 

If you do a tune up use ACDelco brand, these engines are senitive to aftermarket products.

The P0440 is evap code. Normally you can retighten your gas cap. It could be a bad gas cap or maybe you overfilled the tank with gas.

Also, while your at it take off your IAC valve and clean it real good and your MAF sensor.

 

Well I changed the wires and it seems to be good now. On the weekend the cat did go South and I guess I will be replacing it this week. Thanks for the replies.