Need help with cars performance

[240sx_in_209]

Ok well just recently my car has been acting weird. When i first start the car and i step on the gas like the rpm's go down. but it goes away like after 30 seconds. also like in 1st and 2nd the car feels like its kinda jerking when i step on the gas. They were telling me the jerking ness could be that my Catalytic converter is clogged could they be right? I checked my spark plugs they all look good, put a new 300zx fuel filter.

[OutToWinPAHC]

FF is new, sparks look good. I would try cleaning the MAF, and throttle body. It would also be an injector on its way out. Is she throwing any codes?

Bur yeah my guess is Dirty/Bad MAF or an injector issue.

[240sx_in_209]

no codes from the motor my cel is on only because the egr valve. Ill try cleaning the mass tomorrow.. How would be the best way to clean it out? with the can for the mass sensor??

[Superuser]

It could be a pluged egr, i use brake cleaner to cleaner to clean my mas and i dont think that it would be a cat cause that would do it all the time

[Shift__BODOM]

I would urge you NOT to use brake cleaner on the MAFS. It leaves a bit of residue that - if you have a MAFS problem - will make the issue far worse, or possibly short the sensor out.

Now, this is only what I've heard from many reputable sources (me being a mechanic I'm kinda surrounded by them), but nonetheless, err on the side of caution and get the MAFS cleaner. It'll be right next to the brake parts cleaner at your local auto parts store. Also make sure your MAFS is disconnected and preferably out of the car entirely when you spray it. You don't want MAFS cleaner in your intake tract, and you've also got to let it air dry for 5-10 minutes before reinstalling. Canned air can accelerate this process, but be very careful as the MAFS is an extremely fragile sensor. That being said, also resist the temptation to touch the MAFS leads. They'll snap right off and ruin your day in a heartbeat.

As for your problem, stick to Occam's razor. You need to deal with the EGR before you go spraying stuff into your MAFS or replacing your cat. Do a simple operation test, check all connectors, vacuum lines etc.

If you need detailed testing procedures, I can post some links to pages out of the manual, otherwise NICO search should yield some positive results.

Good luck!

Edit:

Here are those procedures

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Modified by Shift__BODOM at 1:27 AM 3/8/2009