This is not Fiero related, but no-one anywhere has come up with an answer, and this bunch of Fiero enthusiats seems pretty bright. Here goes, for the million dollar question.
Have a '88 Mercury Sable, 3.0L,F/I V-6, 4-speed automatic tranny with O/D.
It has a stall problem. In the morning it starts right up, runs great, gets you where you need to go. But, sometimes(lately once or twice a day) it stalls out(usually when hot). Throttle doesn't matter. Idling at a stoplight, or driving down the road, the engine will just cut out. Ocassionally, it will start right back up, if you crank it over. But other times, it will not start, at all. But will 30-45 minutes later. I replaced the coolant temp sensor last week, solved the problem until today(put on 200miles). It stalled, would not start again, but would 45 minutes later, drove it home. I pulled the ignition module(retards at pep boys said they could test out of the vehicle. I pulled it out, spent two hours getting it out, took it in, they need it on the vehicle, stupid phone person). I'm at a loss. The ford computer system, does not give a live computer feed, so putting it on a machine isn't going to help much. Where do I go? I "think" it is heat related. What next?

Check to see if any ECM critical wires on the engine have got scuffed or burned through the insulation. I had the same problem on a Maxima, after months of trying and trips to the dealership a backyard mechanic found a temp sensor wire had rubbed the intake and would short out causing the car to immediately stall.

I owned a Pinto (yes, thank you) and it would quit when the ignition coil got hot. This was twenty years ago, but the mechanic at the time said it was due to a short caused by internal expansion caused by heat.
And since I sincerely enjoyed owning that Pinto I won't make any ford jokes.

I would change the ignition module if i had it out. There about 20-30 bucks i think.
Apply dilectric grease to the back of it.

The state of california is suppose to be sueing Ford because they knew the modules would go bad and the cars would stall and it would be impossible to steer the car for senior citizens.

I own a 87 tbird turbo and that has tons of sensors and its a ***** trying to figure out whats wrong.
I would change that module because they are known to go bad from heat. My mothers car use to stall because of the module but that was a 2.8 chevy.
Try not to take it to the dealer right away, they will run diagnostics and change parts. In a few days, the car might do the same thing and the dealer will want more money to fix the problem.

Guess I should have mentioned this. When the car stalled when I was driving it(didn't have my tools with me) I pulled the coil wire, and cranked the engine. The coil sparked very nicely. I haven't checked for fuel pressure but I can hear the F/P priming when I turn the ignition(plus it was replaced last summer). The ignition module was replaced three or four years ago, but has around 50,000 miles on it. I'll try a new one. I just wanted to make sure I wasn't the only one who thought the module could be bad.

[This message has been edited by fiero56 (edited 02-22-2000).]

56,

Are there any strange symptoms? One in particular that dumbfounded me for quite a while was symptoms of vapor lock. I once had a Dodge P.U. that the back pressure would build up so great that it would stop the engine. After a while (15 minutes or so) the pressure would subside naturally and it would run great again. This problem only caused problems during long constant throttle driving (such as hwy). It also could be helped by "clearing the exhaust" or in other words taking it out of gear and red lining it. This would blow huge plumes of smoke out the pipe. I never oficially determined the cause of this but imagined clogged cat was the culpret. Oddly enough the cat was only about half of a year old when the problems commenced though so I did not want to replace it again. Especially when a new cat installed cost about half the value of the truck!

William T. Thorn, III

William, I drove it around town with the gas cap off trying to eliminate possibilities, still stalled. I stopped off at Autozone today, they are able to test out of the vehicle. I pulled the module off the car again, and it tested bad a couple of times. Got a new one for $25(half what PepBoys wanted for the same maker). It is sitting on the counter wating to be installed. Hopefully this fixes it.

Check the fuel pressure at the intake, if it's low change the filter.