My Xjr went into Restricted Performance when I took it on the highway. The engine has trouble getting pass 3k then it suddenly shoots to 4K Rpm and seems like there is no power that RP Mode comes on. I kept up on my oil changes and main. I don't know how this happen any help will be appreciated
Thanks

 

Have you checked for thrown codes? My gut says induction system, maf, air cleaner, leaks,etc. Then oxygen sensors. But there should be a code thrown somewhere here.

 

I believe it has a vacumm leak somewhere it also sound like a ratling noise if I try to get on it on the highway saw a cam code on the ob2 says the mechanic ... This is really weird changed my oil religiously .. Where should I start ???

 

You need to know what that OBD code was and from there, what it means, find that number and post it back here.

 

PO430- Catalyst Efficiency Below Threshold (Bank 2)
PO420- Catalyst Efficiency Below Threshold (Bank 1)
PO316
PO300
PO308
PO307 } Basically Ever Cylinder Had Missed Fired
PO306
PO305
PO304
PO303
PO302
PO301
PO101 Mass Air Flow or VAF A CKT Rango / Perf

It sounds like a hissing sound over top of the motor

Maybe a Vacuum Leak and Bad Oxygen Sensor

The Car hesitates when I try to accelerate after 10 minutes of driven
Then Restricted Performance

Do you know where I should Start?

 

Possible split hose that is connected to the inlet manifold thus letting extra air into the engine thus bypassing the air flow meter, and confusing the ECU.

 

I tried using Ether by spraying the motor to find the vacuum leak on the intake.

No Progress with that

Do you happen to know any techniques of finding that leak another way??