I'm a bit of a diesel fan and recently crossed over from the VW TDi world and purchased a 98 E300 Turbodiesel. Bought it from the original owner in excellent condition.
I had good luck with chip and flash tunes on my VW's, so I jumped right into a chip tune for my E300 through Speedtuning USA.
Once I installed my ECU returned from Oliver at Speedtune, I experienced a rough idle anytime in N or Drive and a stutter upon rev-down from about 1200 RPM back down to idle under all conditions.
It turns out that MBZ had a factory countermeasure to this complaint years ago, and it included an ECU swap. Oliver had noticed that I had a 99 model year ECU in my 98, and now after speaking to a service writer at Caliber Motors and after reading the following link, I knew the reason why. The ECU I had sent to Oliver had the updated part number to correct the rough idle customer complaints. Follow the link to see a short article in STAR magazine by Stu Ritter:
Suspecting that the new tune from Speedtune did not incorporate this update, I wrote to Oliver about this software updating and my cars history of having it done. His response was that he could tune out the rough idle by increasing fuel quantity settings, but that he would have to charge for a "custom" tune, an additional $200 on top of the $325 I had already paid.
My response to this was to request my ECU be returned to the previous, stock program. I didn't feel that the additional fee to have my car run satisfactorily was fair and I was much more interested in having my E300 run as nicely as it looked rather than having the extra 30HP or so at this point.
So with his verbal agreement to return the ECU to me by the time I returned from a two week trip, I shipped the it back off to Speedtuning. Days later I received a full refund through Paypal. So what is my complaint, right?
Well, now they are holding my ECU until I send them (like AMGAlex's experience with them) a payment of $375 in cash, money order or Western Union. Craigslist and Ebay have warnings not to do business with companies seeking payment like this. This request came from Jennifer (the owner) after they had tendered a refund through Paypal.
One more bit of context: Oliver relayed a story to me that he had a customer with a 99 E300 experiencing the exact same idle issue. The customer had the direction of a MBZ dealer that he would need the updated ECU (the one I have) to solve his problem. For whatever reason, probably cost (Caliber Motors in Anaheim wants $2300 for one and won't sell it over-the-counter) this customer of Oliver's tried the same Stage 2 tune I purchased from Speedtuning and it did not resolve his idle issue, according to Oliver.
Even having had that experience and mine, Oliver and Jennifer, AFTER having refunded the full amount told me their tune IS based on the updated software to address the idle and now I would have to pay them $375 for them to release my ECU that is now put back to the way it was before.
This is not acceptable to me, to have to pay more than originally, or frankly to have to pay at all, for services that I have rejected for good reason.
My E300 has been immobile in my garage for nearly a month now, and I have the counsel of an attorney who suggested I tell my story on internet forums. Everything I've stated here is in print on emails between Speedtuning USA and I.
I will continue to update the forum on my progress, if any, from Speedtuning USA.