You can adjust the fuel mixture using a allen wrench. You should do a search on how to adjust the fuel mixture on m103 engine. On top of the fuel distributor on the right hand side(facing from front of car) there is a metal post. You may have to remove the top. Once top is removed you can take a 3mm allen wrench and insert into post while enginge is running. you push the allen wrench down until you feel it engage and turn to left for lean, right for rich (facing engine from drivers side fender) if you push down too hard the engine will stall. You should use a multimeter to adjust this. I am not sure exactly how to do it but it is covered on the thread about this. I just used the coon tune method of adjusting by ear and driving. Right will increase idle and make mixture rich but too rich means poor accelaration. Make small adjustments and remember where you started. Like I mentioned above there is a thread on how to do this on this or another MB forum, I don't remember which one. Google w124 MB M103 Fuel mixture. Hope this helped. The intermittent starting issue may be the fuel injection relay. I am currently trying to figure this out myself.
I have replaced the Overload protection Relay, Ignition Parts(except coil).
Car will run fine, then stop, sometimes restart, if you take the fuel injection relay out and put it back in it usually will start. I have not been stranded yet but ...Hope this helps

__________________

I didnt know that either. But sounds like a possiblity.

THANKS so much for the personal testimony. I read the fuel adjustment post somewhere, but didnt take noptes. I will take a stab at that. It sounds interesting. Dont trust the boneyard for electronic replacement parts, so may have to put out $$ for new OVP and fuel relay this week.
Thanks again. I am gonna give adj a try!!

Fuel Mix adjustment seemed to help a LOT! Still not where it needs to be but getting tolerable to drive. warm engine runs different than cold, so gonn alet it cool down before I make any firm conclusions. Starting is still hit and miss and probably wouldn't spin a tire on a gravel road, but it is better than bfore!

Ok. Cars runs like crap when it's first started. When it heats to 80 then it runs much better, but still wouldn't pull my finger out of a jar of Vasaline. Coolant temp sensor info ...havent been able to find those values to do a check .
Probably go ahead and order a OVP relay.

i had a similiar issue on my 89n300ce,i replaced both fuel pumps due to low pressure output,i replaced the ovp,it was flucuating from 12-14 volts,both fuses still good,new fuel filter,still had issues,then the o2 sensor needed to be replaced,it makes a big difference when you add a new o2 sensor,the car starts up easy now,and has full power,prior it was running very ruff when cold,stalling out,bucking on take off,hesitating,loss of power,you may also want to have your eha checked,replaced then have the air fuel ratio recalibrated,good luck,also you may wanna check proper operation of the fuel pump relay.they get old hot and the solder breaks.

Thanks for that info. I am gonna try to find a mechanic who might have equipment to read codes and see what it says. I believe that those same items might need to be replaced on mine.

Took the 1992 300TE to a reputable guy here. He did lots of testing and found the intake vacuum pressure measuring only 9-10 inches when it should be 15-17 . This throws off all the sensors etc causing the problems I have...mostly running very poorly. He chased all the lines and scratched his butt and is not sure. Never had this problem before, he says. Suggests that the valve springs may be weak ...if the engine had gotten too hat, maybe, but no evidence of previous head removal or repair. I dont think it's likely as the engine will rev out, but just slowly. Valve arent floating, I dont think. Has ANYONE ever had a similar issue or have any suggestions as to where to look.
Thanks

i would check int the fuel pump relay,the ovp and the eha,also the fuel accumulator,these can all cause these issues.

Took the car to a Bosch service center in San Antonio. Took them about an hour to diagnose. They recommended new injectors and a low mile Fuel distributor. I contended that I was not confident that it would be the cure, but he assured me he would buy the parts back if it failed. It did not fail. The car starts easy and runs great! Couldn't be happier about it (unless it would've been cheaper) ha! Now I can tinker with a few cosmetic issues and quit worrying about whether it's gonna make it home.
Thanks for all ya'lls suggestions. Now on to the next issue!