Mercedes: Will you please help me? Because Id really appreciate it!, road speed limits, mercedes 420 sel

Question
I have a 1986 Mercedes, 420 Sel.  I'm wondering what's wrong with it.  The car stalls if I turn too fast while driving.  It stalls if I push on the gas too fast.  As long as I don't push the gas too fast, and it's cold outside, it's fine.  But when it's very hot, it keeps on stalling.  But as soon as I get Premimium gas put in it, it seems fine, as in not stalling.  But it's not low on gas.  After it stalls, as long as I put enough gas in it, it seems to not stall.  Or if after it stalls, I just let it sit over night, and in the morning when it's cold it doesn't stall, as long as I don't push hard on the gas, or turn too fast.  I was wondering if it might be the fuel filter, or if the fuel injectors need to be cleaned, or if something with the radiator is also causing it?  Thank you for any suggestions!

Answer
Shanon,
Hot weather plays havoc with fuel delivery and proper mixing. I would suggest a tune up beginning with "Techron" Black bottle fuel treatment. Preferably when the tank is down around 1/4 full. Pour in the additive and fill the tank.
The new Ethanol laced fuels tend to cause more problems than the old high octane fuel offered when your vehicle was built.
If that does not help. New plugs should be installed, unless you have already done so.
The plug wire heat shields  require a tool to pull them off the plugs because of the confinement. Borrow or rent one. Trying to remove the wires by pulling rubber will only damage the sires.
I would also install a new air filter to make sure the engine is breathing properly.
The engine is an air pump and must have proper air coming in to mix with the fuel to create the proper mixture for clean burning.

If you are not driving the vehicle out on the interstate or up to road speed for more than 20 minutes, then take it for a long drive at road speed limits. Slow driving in traffic, cause more fuel to collect in the cylinders and tends to foul the plugs, this short distance driving is also a problem for the catalytic converter that need to rise to high temps to process the pollutants.
If you live in a hot climate, then you may want to think about a cooler heat range plug.
Be sure to learn what the plug number should be for this vehicle.
No fancy plugs necessary.
Good Luck
Le me know what you find out.