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Thanks to all here, I also barely avoided an expensive fix. Bill's technique works. Same situation, my 14yr old son ripped the key out in ACC position and the tumbler was messed up, wouldn't turn normally. Nothing would budge it. Dealer quote was in $500 range, locksmith was just as high with no guarantee, yikes! Read further here and... Added some graphite powder, Tried rotating several small "jeweler" sized screwdrivers in the upper and lower slots of the actual key-ways of the cylinder. I just fished around in the 2 slots with them. Then I noticed that my 3/8inch "inner" tumbler was indented, but now it was now able to be moved outward. [bTW I now believe the indented tumbler is my actual problem, the 3/8 inch tumbler is not "popping back" out to its correct position) it is left in the indented position with the key out. This also explains why a hammer tap makes sense. I might also suggest, trying to grab the tumbler with needle nose pliers and coaxing it back out.] ....and then when the key was reinserted it was good as new. THANKS everyone, I owe you! graphite powder and careful use should avoid this

Forgot to say, yes the intermittent P0171 will show as a CEL (Check Engine Light). The P0171 and CEL will register but only intermittently with a dirty MAF. I used a scantool to reset, and P0171 and CEL stays OFF for a few days, but eventually it will return. But the driveability symptoms I mentioned above will persist with or without CEL until the MAF is properly cleaned [or replaced as Lexus would have your do]. about $150 in parts, + labor ??? DIY for $8 Gumout Throttle Body Cleaner and 1/2 hour, EASY. ALSO, more good news....I believe a battery disconnect will clear the CEL. I do recall resetting CEL with battery disconnect once :)

I had P0171 which is "System Too Lean (Fuel Trim)".... and thx to this forum and others I decided to clean the MAF with throttle body cleaner, instant success. I used Gumout Throttle body cleaner and then used compressed air on "low". This is a 1/2 hour job. Symptoms were: Early model RX300 (one of the first) poor shifting, hesitation, loss of top end under uphill "freeway" loads. Good luck everyone.