1998 E320 runs rough
 

Generally starts fine. But engine will start running rough if I accelerate too hard.
Turing ignition off and on immediately while driving instantly corrects problem.
could use a clue ?

crap contacts/grounds in the Throttle actuator, buggered up fuel filters, Fuel quality issues, arcing wires, due for a tune up, throttle body dirty, MAF sensor issues, Coil pack(s) Faulty (if equipped).... the list is endless, how many miles are on your car? Sedan? Wagon? Coupe?

Edit: had another thought. Fuel pump(s) not putting out enough pressure

You left out the part where the CEL flashed on and off. ;)

The "rough running" is because the ECU has turned off cylinders to prevent damage to the cats. They reset when the car is shut off and restarted.

Your post is cryptic enough to include most every possibility.

How many miles on it? What maintenance have you done (and deferred)? How long has the problem been going on? Has it gotten worse? What other symptoms have been cropping up along the way? Have you always run premium unleaded?

No matter what else, the first place to start is to check the codes. That will at least give you a starting place.

Good luck.

+1 on check codes.

Get a OBD scanner ($50 at auto stores or online). Scan and write down codes stored. Erase all codes. Drive it for awhile and recheck. Post those codes for advice.

Just under 200K miles. Wagon

I got the care from my father when he picked up a new ML350, and 4 months ago. It has had the problem since I got it.

The Dash has a check engine electronics message.
I will get an OBD an pull the codes.

I believe the fuel filter has already been replaced.

I also have a 1994 E320. The MAF fails on that about every 18months. The symptoms are almost the opposite of this.

If a CEL light flashed i have never seen it.


Thanks.

the Check Electronics message in your Gauge cluster is a form of it, but, on the bottom right corner is where a little yellow check engine is located, thats where it is on my 99 anyways