P0446 And Acceleration Vibration / Jerking

[Promod]

The Patient: 1999 RX 300 with 210,000 miles

The problems:

1.) Under normal acceleration, at times it will act like the power is of/on like a light switch. It's not a miss, it's more like a surge off/on. This typically happens in 2-3 gear.

2.) Under acceleration, the engine is very rough. This may actually be the transmission and not the engine, I don't know for sure.

3.) Noticed that the headlights flicker.

4.) Only code that keeps coming back is P0446, no others (I have an Actron CP9145 I keep in the car)

What I have done to the vehicle since purchasing it a month ago

1.) Oil change with Mobil 1 and a pint of MMO

2.) Pulled front Oil Control Valve and cleaned (did have misfires on all front cylinders) gone now.

3.) New PCV Valve / Air Cleaner

4.) New NGK Plugs (OEM recommended)

5.) Pulled front valve cover and oil pan/pickup to check for sludge and they was as clean as one would expect for the mileage)

I really like this vehicle and would like to get these bugs worked out. If anyone can offer suggestions on what to check for I would appreciate it.

Thanks in advance!

[lenore]

hERE IS a posting from clubl lexus that may be worth checking out...

http://www.clublexus.com/forums/rx-first-generation/246678-check-engine-code-po-440-po-446-a.html