I have a 91 300 e 2.6. For the last year and a half, about maybe 4 or 5 times a year, when I am stopped t a light or even slowing to a stop, the car would stall. I would immediately turn the key and it would restart and no problems. Now lately, he would start fine the first cold start and then after driving for a while maybe 10 minutes, i would shut her down go into the store and then nothing. she wont start. this happpend about a week ago. i got picked up and left the car there and returned about 4 hours later with a friend to tow me back home. I decided let me try her. Sure enopugh she started and i drove home. today i went literally 1 mile to the store about 4 minutes and then shut it got out went to start again and it wouldnt start. it turned like it would but wouldnt. i also was getting what seemed like a backfiring from the carb. i waited a little bit and triued again with the same rsults. i kept trying becasue each time as i was about to turn the key back to the off position, it sounded like it would start. as i was turning the key i tried pumping the gas. after a few times doing this it finally started but ran rough like it wasnt getting enough gas. after like 7 or 8 seconds it ran smooth. i drove back home and shut her off and hse started right up again.. i then gave it a little gas and it had a hesistaion but then the rpms went up and it ran fine. I NEED HELP!. I have read the forums and see it could be the crankshaft position sensor, the cold start relay, the ovp , the mas relay or faulty fuel pumps. I am not mechanically inclined in the least. Where do I start? I did look behind the battery and removed the cover and did see two large silver square boxlike things. one said mas on it and had a knob on the top. I have no clue what these are or what they do or if the mas relay has relays inside as some posts said. ANy help would be great. You can also email me at sean11784@aol.com. Thanks

based upon description I would put new spark plugs in (the new Bosch copper +) and a new coolant temp sensor. Should be less than $60 all told, that fixed my 1990 300TE like a champ...seriously...that's where I would start...good luck

Both of these items are behind yourf battery. I am not sure if your year has them. Someone else can confirm...Also, when was the last time you change your fuel filter...?

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J.H.
'86 300E

Check the coil.

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2012 E350
2006 Callaway SC560