Topic: Engine idles rough surges and runs rich

[5.0world]

Hey can anyone give me a hand with my 1988 Mustang GT I recently pulled out the original motor and replaced it with one from a 1991 GT which had a mass air flow and the old one didn't so when I replaced it I just set it up the same way that it was would this cause these problems that I'm having? Also the previous owner told me he had put on a new computer would this possibly cause the problems aswell? The car starts on the first crank but idles very badly and sounds like it's missing and when driving it surges very agressivly but still responds quite well when you hit the throttle. Any help would be greatly appreciated as I just want to get my baby on the road thanks.

[dwight]

Hi,
  I have a 1990 5.0L LX and it has the mass airflow sensor setup. I accidentally forgot to plug the mass airflow sensor in one time when I was putting it back together after removing everything to get at the plugs and the car would not even idle. It would start then just stall out.  Ok, I don't drive this car much. It has 9,500 miles on it and is 21 years old. I had no issues with anything until I filled it up with gas a year ago and then drove it. It sounded all right just after filling up. But it sat for a month and then when I tried to start it, it started surging violently. 500 rpm to 2000 rpm and up and down and up and down.  Well, our gas is now laced with 10% crapinol (ethanol for the uninitiated) My car HATES crapinol. But I did finally find this stuff at the local commercial lawn mower sales place. It is an additive / stabilizer specifically designed to reduce issues with this crap. Ethanol is the bane of my existence. It has messed up the  carburetors and fuel lines in a boat, two weed wackers, two chain saws and one commercial mower. Anyway, this stuff caused exactly what you are talking about. But after using this commercial mower fuel additive, the car runs as it always did, perfectly smooth and quiet. My 01 Accord coupe had issues with this ethanol laced gas as well. It's fuel economy dropped from just over 30 mpg to just over 28 mpg. It doesn't work well in my '04 Nissan 350Z either. But it is now all we can get here in North Florida. Some stations use more then others. I have found a couple where the gas smells more like real gas so I go there. Guess my nose for ethanol must be good because when I fill up at that station, my fuel economy is better, the exhaust doesn't stink like spilled whisky and the cars run smoother. Man I wish they would give us a choice of buying real gas, E15 or E85. Some of us have cars that just plain do not tolerate much of any ethanol in the gas. Anyway, the fuel additive is in a clear blue bottle. Don't for the life of me know the brand. I'm not at home so I can't check. But any place that sells real commercial lawn care equipment will have such an additive.