98 ford taurus stalls and shuts off while driving but will restart

Try unplugging the mass air flow sensor on the air filter box. If it don't stall, change the sensor.

IAC idler air control valve sticking, bad air filter or a vacume leak.

Sounds like vac hose on brake booster has come off or is cracked.

I had one with a poltergeist in it. It might run fine for weeks and one day when it's above 90 it would shut off. Let it sit for about a half hour and it would run fine for a few days or weeks. The Ford dealer could not figure it out. I found out it was not getting fuel even though it had a new pump and filter, same problem. Found a good used fuel regulator and that seemed to help out as the old one was full of rust. It shut off about 6 months after that and restarted & I soon sold that problem.

IAT sensor is the Intake Air Sensor.. It could be temperature or amount and as the engine is stalling, I would suspect that the sensor is not measuring the amount of airflow correctly..Substitute a known good unit as these sensors are not a repairable item..

check for vacuum leaks. clean idle air bypass passages on throttle body, they control air at idle needed to maintain idle speed.

SOUND LIKE THE TRANSAXLE DRIVE CHAIN AND DRIVE SPROCKET BEARINGS IS SHOT.

check for vacume leaks most common problem for symptoms listed its hoses on engine look for dryrot cracked, or broken hoses or lose come off

its in the timing ...whenever you start it it sits and idles fine but when you go to put it in gear it dies...the timing needs to be repaired. its a guaranteed solution.

Here is the most common cause of surges and stalls and low idle, it is the idle speed control air-bypass valve and throttle valve, they get full of gunk over the miles and cause idle issues (stalls) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.