1996 Ford Taurus SHO 3.4. Intermittant starting problem. Welded cams. First instance a couple of months ago. Had it towed to a local shop. Once there the car started right up. They kept it for the day starting it up about once an hour. About a month ago it did the same thing. From the towing incident my conclusion was to, basically, rock the car. That worked! Yesterday, same problem. No amount of jostling helped. Won?t start. So far: Checked the fuel filter, fuel pressure - both good; replaced the cam sensor; and, about to replace the crank position sensor. As of today, it is parked. Will not start. An issue that may or may not be related. On several occasions, after running the car for about 50-100 miles, it will be difficult to start after it sits for anywhere from a short stop at a grocery store to a couple of hours. It will not idle. After holding it at a high idle (2500-3000 RM) for a minute or so, it will idle fine.

The intermittent hard strarting may be due to a bad prom in your computer module. I have the same problem wiuth a 2000 Taurus and foiund that there was a Technical Service Bulletin listing specific module codes to look for in the computer. If your car had that specific module, it needed to be replaced. As for your current starting problem, you should check your Idle speed motor. If it sticks shut, it will cut off all the air to the motor and prevent starting without holding the gas pedal down a little bit will "crack" the throttle open and allow air into the engine so it will start. If it is sticking, you can remove the throttle position sensor, clean it out with WD40 or CRC and then energize the sensor by plugging it back in and energizing it by turning the key to the "on" position. If it is working properly, you should be able to blow air through the two holes when the Sensor is Energized, and no air when it is not energized.

Try replacing the gas cap,may be vapor locked,check throttle position sensor by holding the pedal to the floor while cranking,if it starts then replace the sensor,if not it probably works