Hello,
Well if you remember my 1991 300e with a 3.0 will go into what I call Stupid Mode where the car is down on power and will shift hard then it clears up and runs great for days or hours then may repeat Stupid Mode. After I arrived at my friends repair shop I could smell gas and noticed there was gas coming from out of the fuel door which was odd because I did not get gas. The gas cap was on correctly but that is where it is coming from??? I installed a new fuel filter as was suggested and also checked the ground wires under the entire car finding all were tight and in good condition. I did an oil and filter change and replaced the fan belt because it was worn. After this I started the car and it ran great then after a short test drive it went into Stupid Mode again. I was also told to check the volts when it did this and they were spot on?? So if some one has a different idea or something else I should check please let me know!! Some one here asked me to report back and this is what I have found.

When it goes into so called "stupid mode" is it hitting on all six cylinders? Do you have two fuel pumps? Is one of them shutting off and causing fuel starvation. I'm trying to figure out what you mean by stupid mode, if it's actually a power loss or if it feels like a power loss due to a missfire from lack off spark or bad fuel delivery.

Hello,
Well it seems to be running on all six. The car has two fuel pumps. I will say that yesterday it did seem to be running rich when I started the car on the lift after I installed the new fuel filter. But once on the ground it cleared up ran great for about 15 miles then went into Stupid Mode for about 4 miles then it is like you turn on a switch and the car runs great???

Well I think it is the fuel pumps because I just tried to start the car and it acts as if it is out of fuel and will not stay running. So it makes sense that when it was running that one of the pumps was shutting down and then coming back on.

That's a strong possibility. You can check to see which one is drawing more amps. Or you can listen with a probe or just feel to see if one is not running when in "stupid mode" Having one pump out may certainly make it hard to keep running or buck during acceleration.

Now today I started the car and it fired right up and ran flawless. I drove it about 10 miles and it never missed a beat. Damp and rainy here today so that has nothing to do with it. I am still going to put new fuel pumps in and see if that is it.