If it ran well before and does not run well now one might suspect an air leak in the intake tract between the MAF sensor and throttle body.
Any air leak below the throttle body should show up as a rough or slightly rough idle.
I would side with @VDCDriver. Go back and check your work. It’s easy to forget to plug something in, or reconnect a line somewhere. We’ve all done it!!!
And because you say it did not help with the oil leak…check to make sure some vacuum line or wire did not make it’s way under the valve cover while you were installing it, and it is keeping the cover from tightening down properly.
Yosemite
I think just about any V6 Honda Odyssey or Accord, Toyota Camry or Avalon, Lexus ES or RX Series, Ford Taurus from 85-07, and many many others.
Could be…Since the Honda’s we owned were 4-cylinders…and wifes Lexus has been extremely reliable…no need to examine how the intake manifold is installed. I only work on cars as needed.
Last V6 I did any engine work on was my GMC-S-15…I replaced the valve cover gaskets on that engine at least 4 times. If I had to remove the intake manifold to do that job…I would have sold that pice of cr*p vehicle a lot sooner then I did.
Never seen a design like that.
Then obviously, it doesn’t exist…
My Insight (4-cyl) requires intake manifold removal for valve cover removal.
Still waiting!!!
wifes Lexus has been extremely reliable…no need to examine how the intake manifold is installed. I only work on cars as needed.
If you have ever replaced the spark plugs on that ES350 or your 4Runner you wouldn’t forget the manifold design, someone else must be working on your vehicles.
If you have ever replaced the spark plugs on that ES350 or your 4Runner you wouldn't forget the manifold design, someone else must be working on your vehicles.
And you’d be dead wrong. Why would I be looking a the intake manifold to replace the spark-plugs?
Removing the coils and spark plugs from the rear bank would be much easier without that large manifold.
It’s a lot easier when you remove the cross bar in the back.
Just happened to think of this discussion as we were removing the upper intake to replace spark plugs on this 2005 Hyundai.
Nice picture!
What’s that red thing in the upper left?
Please don’t tell me that’s one of those cheapo low-taste “double” wiper blade assemblies . . . I thought those went out of style in the early- or mid-90s 
@db4690 yeah, we were marveling at those wiper blades and thought the same thing…where the heck do you get those things anymore?
After doing the plugs and wires work we moved on to an electronic complaint involving the interior of the car. What did I find? The car has been wrecked and repaired using junkyard parts, including a steering column and steering wheel from a different car, with mismatched wiring. So now when attempting to set or cancel the cruise control the radio will change stations or lower the volume.
Suggest to be careful when changing the radio settings while driving on the freeway. Whatever you don’t, don’t try to adjust the radio clock at 65 mph!! … lol
Some good diagnostics on this thread. Good job!
A faulty MAF will put the computer in limp mode.
I recently had the same problem , the RPMs wouldnt go above 2,500 rpm`s. I back probed the MAF wires with a volt meter, it had 12.8 volts going in and 0.01 volts coming out on the ground wire and the reference wire going to the computer.I replaced the MAF and the car runs fine now.