Anyone ever experienced this? I used OEM spec NGK ILFR6A Iridium plugs and was meticulous to not cross any plugs wires. I checked the intake to ensure that everything was connected fine with no leaks. Any ideas what the problem could be? The motor runs smoother than before. I hate to take it in to the stealership if I don't have to.

first step would be to dump the codes.......a stop at Autozone and they will do that for you if you dont have a reader. Post the info here for help

if the old plugs were extremely bad your ecu probably had learned their resistance and adapted. there is a das reset procedure sometimes used when installing new plugs. if the car is running fine, it could simply be a random misfire code because the ecu needs to learn the new plugs but it's not anything to worry about. regardless, it's all speculation until you follow hotrodneb's advice and report back to us with the cel codes.

could be maybe the gap on the spark plugs or possably a bad wire or wires not pressed all the way in for full contact not sure if u checked that out or not, best thing to do is scan the ecu and see what code it shoots back at ya.

Do you need to change the cables everytime change the plugs ?
I thought its for 100K miles the plug as well as the cables.

Did you gap the plugs correctly ? Do as others suggest and have the codes read.

SA stated that plug change interval on the E AMG cars was 60,000 miles and plug wires were 100,000 miles. I changed both at 50,000 with no issues at all.

I know you said you checked the intake for leaks but you also want to check the hoses as well. I had a CEL when I change my plugs and it turned out that I had a leak underneath the driver-side plenum (not visible).

Under the driver side plenum, there is a L-shape metal hoses and the rubber hoses only goes into it a little bit. It is very easy to get this hose loose in the mist of installing back all the other hoses.

Turn on the engine in the garage and listen to see if you hear any "HISS" sound. If you do, there's definately a leak somewhere. If there's a leak, spray a small bursts of carb cleaner into the area where the noise is coming from to track down the leak. When you hit the right area with the carb cleaner, the engine will choke.

Also try to pull the CEL codes as well.

Thanks for all the suggestions guys! My initial thought was that there was a vacuum leak somewhere as the engine seemed to be idling a few hundred rpms higher than usual both in neutral and engaged in drive. I was meticulous in the plug change and ensured the .8mm gap for each plug. After I realized the CEL, I had the engine hang at 2000 rpm. Know that was not right, I figured that it had to be something electrical so I sucked it up and went to Penske in West Covina. They have indicated that the "entire" accelerator assembly needs to be replaced!? My guess is that the TPS went out, but if they're replacing more than that and my warranty covers it, so be it.

I didn't know that VatoZone could pull codes, thanks for the great info!

be sure to ask them for a printout of the cel's!

Def will do. Vacuum leak cannot be fixed until next week as the hose has to ship from Germany. ECU was going haywire trying to adjust idle speed and the throttle position sensor was also causing some problems. Not excited to be w/o my baby for a week but am glad its nothing major and not attributed to something I screwed up on.