Hey guys. My car seems to be stumbling when I accelerate. the instances were when I was accelerating onto a ramp to the freeway in second gear and the car started stubling around 35mph. The second is when I was accelerating up a hill in thrid gear. I switched to second and it seemed fine. I shifted to thrid and it stumbled again.

I'm not running out of fuel because I have about 3 gallons of fuel left. I changed my oil and spark plugs about 600 miles ago.

I also got the cat replaced about 1000 miles ago because the catalyst inside crumbled. From the sounds of it there seems to be something clogging my exhaust again. Could a clogged cat cause this?

I'd check the fuel filter

If the cat has failed the the stuff in the cat normaly clogs up the muffler. Just get under your car & hit the muffler(s) & see if it rattles then you will no if that has happend. But this normaly happens sttaight after you fit the new cat.
Coops

there's a 40 mph sensor that does something for emissions, mine had a problem like that and i think it was vacuum lines hooked up wrong or something.

sorry i can't be more specific it was a few years ago, but the fact it happens around 40 mph makes me think it's worth a look. Yours may have some other problem.

Thanks for the reply guys.

B210Sleeper, I do not think that would be a problem. I've accelerated my car in second gear to 40mph plenty of times without a problem.

I'll check the fuel filter and muffler the next chance I get. Or my mechanic will. Thanks.