2005 Caravan SXT. Engine light on could not retrieve a code.
Works fine but hits "wall" at 3500 rpm, shudders.
Lifting off gas bringing rpms below 3500,... works fine again.

Runs fine as long as I keep eye on RPMs.
Any thoughts?

You can check for codes using a scanner or the key dance. Try both. I would suspect either a fuel or timing issue. Maybe a pump on it's way out that can't handle high demand or a ckp sensor or harness issue. If you can get a real time scanner you may crack this.

You can check for codes using a scanner or the key dance. Try both. I would suspect either a fuel or timing issue. Maybe a pump on it's way out that can't handle high demand or a ckp sensor or harness issue. If you can get a real time scanner you may crack this.

Thank you, gives me a place to start.

Could be something as simple as restricted intake airflow. The exact same thing happened to me once. Try running it without the air filter and see what it does. If it runs good then you know it's time for a new one.

Good luck.

my bet is on a partially plugged cat converter. mine hit wall ~3000rpm.

Could be something as simple as restricted intake airflow. The exact same thing happened to me once. Try running it without the air filter and see what it does. If it runs good then you know it's time for a new one.

Good luck.

Thanks, I did this, no such luck.

Using the on-off, on-off method, I got the code P0016 Cruise. Any thoughts?
Thanks.

Thanks, I did this, no such luck.

Maybe it's the cat, then as Warrenoutrides suggested. have someone rev it up while you hold your hand near the exhaust and feel the output. obviously, don't touch the exhaust if it's hot. you may have to compare to a good car to notice any difference in the airflow.

p0016 cam and crank timing misalignment....95% broken flexplate....

Have to agree on the probable flexplate. I've been seeing these pop up with regularity lately. You can remove the inspection panel on the transmission and inspect it. This is probably the post that taught me about them relative to the P0016 code: http://forum.chryslerminivan.net/showthread.php?t=10581