So, here is the setup:
I am driving my car on the freeway in 5th gear at around 60 mph.
I slowly press the accellerator.

Here is what happens:
The car slowly accellerates up to about 63mph, then a different tone is heard and there is a vibration which sounds like it comes from the exhaust headers, then the car drops speed and rpm down to about 61mph and re-accellerates.

What the shop says:
This is normal and caused by the dual intake plenum.

What I say:
I have never felt this before and sounds like a new thing to me. I am able to reproduce for them and they say that all of these car are this way.

Does this sound right to you? Anything I should ask them to do?

Thanks for you help,
Chris

what caused the drop the in speed? did you let up on gas or the car won't accelerate anymore?

try another shop or dealer for diagnosis.

The car does it on it's own with constant throttle application. Interesting that teh dealer says this is normal, but no one has responded to me....

Thanks,
Chris

if the intake plenum is the problem try this since the plenum are usually rpm activated keep car in a lower gear duplicate exact rpm where stumble occurs in fifth and see if it is duplicated in third.

how many miles on the car?

is car under warranty?

try a different E430 on a test drive

60k miles on the car
Not under warranty

They are telling me this issue is on all E430s. I guess folks don't have the same experience? I didn't notice it until recently...actually while still under warranty.

Chris

Mine is doing that now.. But my CEL is on. I know I need a MAS. Maybe your is going bad..

__________________
Peter L. House
1998 Sport E430
Azure Blue
110,000k Miles

1987 Oldsmobile Cutlass Salon
V8 Bucket Seats
Factory Moon Roof

Tested mine ('99 E430) today, no hesitation or anything abnormal, accelerated smoothly.

Peter