300ce fuel starvation?

91 300ce has been shaking, especially violent when in gear. Before it got worse, it would hold back when going uphills or accelerating. I replaced the fuel filter but it didn't make any difference. Might I be
looking at fuel injector problem, or does it just need a tune up?
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How many miles on the motor and how many since the last tune up?
I suspect one or more of the ignition components: coils and / or the spark plug connectors, especially if the shake rattle & roll occurs cold and hot at both idle and during power demands.
Any codes?
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Our W124 chassis has a known problem with Overload Relay Protection... if you never changed it before, I'd start off with this one. The erratic nature of failing OVP can cause numerous symptoms including the one you are having.
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Looked at the spark plugs. One of them was caked in oil, no idea how it got in there. There doesn't seem to be any leaks so it must have spilled in there somehow. I cleaned it up the best I knew how, but the plug needs to be replaced. Any tips on cleaning the oil out of the hole?
After cleaning the plug the car ran better, and after a few seconds it was back to it's old self. But once I turned it off and back on again, it started back to shaking only now it won't shake in P or N.
I still suspect the overload relay may still be a problem. Is there a reliable way to test it with a multimeter?
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Nope... no reliable way to test them. Look, if they are indeed 15 years old... don't you think it is time to change it?
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Of course it's time to replace it. But what's the best way to clean out the hole where the dirty spark plug is?
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With spark plug in place... I would spray some degreaser like Simple Green or equivalent into the hole and then use compressed air to blow it out and rag over the hole to catch all liquid debris and final blow into the air... It is a messy job.
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Tiger wrote:

Right, but you can take it out and pump pins 1 (30), 2 (87E), 4 (30a) and 6 (87L).
If it runs OK then, the problem is OVP relay.
Mind that when doing this the ECU is without overvoltage protection. Under normal conditions that is not a problem.
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