XG-350 REV limiter/Fuel cut-out on 3.5 liter
 

I have a 2005 XG-350L that has thrown many CHECK engine lights. The dealer has changes O2 sensors, coils, and computer. The vehicle still throws the light when accelerating onto the freeway @ 65-80mph. The light goes off when you let off the accelerator, however the vehicle is still not running like it once did. It lacks power and runs rough. It has 69K on the ODO. I have recently noticed that when the car is in park and I bring the RPM up, it starts to break up at about 4200 RPM, the engine will not go beyond 4400 rpm in park. My question is: Is there a rev limiter or fuel cut off for this vehicle and engine ? (3.5Liter V-6) I ask because I just noticed this and I would bring it to the dealers attention, fix that and we fix the problems, if........ the car does not have the limiters.
All who read this, if you know for sure there is NOT a limiter I want to hear from you.
Thank you.

R/
Joe-Love my Sonata, not so much my XG

I thought this behavior of revving the engine while in park was a bit odd on my 04 XG, that it seemed to shake violently after about 4K RPMs. I asked my brother in law, who is a master mechanic at Ford and he said that most newer cars have a feature that limits revving through cylinder de-activation while the car is in park or neutral. They do this because there is no real diagnostic or maintenance reason to rev the engine that high while the car is static. This limits user damage to the engine and in no way harms the vehicle. Put the car in drive and second gear and hit the freeway. You will easily see that the rev-limitation is not present. If it is still there, then you have other rev/fuel delivery problems.
This is the way it was explained to me.

Thank you Sam_XG350L,
I am confident that the vehicle does have a rev limiter to limit engine speed above 4K RPM in park or neutral. At first I found that strange because I have owned many vehicles, to include high performance type, and none ever had a rev limiter, with the exception of my Buick GN, and that was more of a car speed limiter, not engine. Anywho, the real culpret turned out to be a bad tensioner that was missed when the timing belt was replaced at 58K. The belt ended up jumping a couple of teeth, thankfully it did not jump enough to cause a valve to meet a piston. So the problem is fixed, the car has a rev limiter, and I once again enjoy the full power and comfort of my XG. Thank you for answeering my post.