My truck idles fine..but when i put it in reverse or drive it dies..
i reset the computer and cleaned the air filter but it didn't help..

its a 98 4.6 auto

 

I don't know if the 4R70W does this or not but there's a TSB for the 4R100 stalling when put in gear.

The problem according to the TSB is that the transmission filter has become detatched or loose.

If you don't come across anything else, 6 qts of Mercon V cost a lot less than having your truck towed to the dealership.

 

Check the tube that goes from the MAF to the throttle body. If its loose or cracked it can let in a big gulp of unmetered air when the engine moves a bit as you put it in to "R" or "D". This is a common problem on other models of Fords, but seems to be less of a problem on the trucks. Still worth a check before you pay for a diagnosis.

 

Well i took a look under the truck and my rear seal is leaking.. then i checked the fliud and it is below the crosshatched area on the stick.. i'll go buy some atf and see if it works...

 

Well it didn't work.. If i hold the brake and give it gas when i put it in gear it will go...but when i come to a stop it dies.. fuel filter? spark plugs? O2 sensors?? it has over 100,000 miles on it..

 

Did you keep the trans in drive when off the highway(under 50 MPH) and how often did you change all 13 ouarts of fluid? Hope its not but you may have a smoked 4R70W. Good luck..........