My 02 IS300 MT starts shuddering at 4k RPM in any gear or weather condition. No check Engine light. I have a aftermarket intake but everything else is stock. Has anyone else had this problem??

 

give a little better description. what exactly do you mean by shuddering. what are your RPMs doing at this time?

have you done all of your basic and regular maintenance?

 

car drives fine in each gear until you hit 4k RPM. Then the engine has very little power. Rpms stay the same. If you keep your foot in the throttle the RPMs will go up but very slowly. Possible lack of fuel/air?? Feels like it is has a misfire.

Just bought it in January. Had everything replaced...spark plugs, T-Belt, all seals and fluids.

since i posted the original comment my check engine light has come on. Pulled the code and it looks like i need a cat. not sure if it could be related.



Not sure where to start>>>>>>>>>>>>>>>>>>>>>>>>

 

cats are bad for coming apart and lodging themselves in the exhaust. This could also be caused by a mass air flow issue and with the car going lean constantly could cause the converter failure also. I would check the MAF sensor and then the Cats after that.

 

Will do..... gracias

 

Could u fix all this with an o2 pnp, headers and an exhaust?