My 2005 Buick Rendezvous will not go over 4000rpm when idle. When on the highway, it loses power when I try to quickly accelerate.

There is no governor.
You cannot adjust speed control.
What exactly are you attempting to accomplish.

Well the codes are not related.
Code 135 is for a problem with the heater circuit in the front O2 sensor, and code 301 is a lose of power on cylinder one.
Code 135 could be the sensor or the power source for the heater, and code 301 could be fuel or spark related.

Most probably some ignition cable to the spark plugs.

I would suggest the catalytic converter is at fault here, Many a car has been scrapped because of this problem.

First have a diagnostics test done. It sounds like the throttle position sensor is out, or the EGR valve. The EGR valve will most likely be the cheapest part for replacement, and the most likely issue; however this is why I suggest a diagnostics test. If you cannot afford a technician (recommended) then I suggest having a local parts dealer (call around first) do this for you (usually a free service) to identify which part(s) (codes will be listed) need replaced.
Please let me know if you need further assistance.
carsandcomps

Start with replacing the fuel filter. When they clog up they will keep pressure but not flow.

SOUND LIKE IDLE AIR CONTROL VALVE PROBLEMS OR DIRTY STICKING THROTTLE PLATE OR BINDING MISADJUSTED ACCELERATOR CABLE.

I had the same issue with my '04. Ultimately, it was a transmission issue. Had my transmission rebuilt. no more whistle. it sounded like a toy truck before, now it sounds like a big truck. Vroooom!

BUICK RENDEZVOUS IDLES UP REALLY HIGH...WITHOUT PRESSING GAS. WHAT IS THIS?

have you tried cleaning out the throttle body as i had a similar problem and this worked