'98 Ford Expedition will not engage when I put it in Drive

Okay, two things.......dirty MAF sensor(clean it) and idle air control valve. don-ohio

It seems like this 98 is well known for this, i have a 98 as well and never had this problem YET? god i shouldnt have said it. but in my fuse cluster on the side of dash inside behind drivers door is a fuse in the 26 th position (10 A) that says its the electronic shift relay,electronic shift control module,power window relay,interior lamp relay,battery saver relay. CHECK THIS FUSE, also pos 27, ( 15A) it says DLR,back-up lamp switch,DTR sensor, GEM, (generic electronic module) ELECTRIC SHIFT. check this fuse also. Under the hood by the battery there is another fuse box inside there is a "POWERTRAIN CONTROL MODULE' I dont know what this is but it says what it says, it is located in the # 6 position and is a 10a fuse...." Be careful if you rev the gas as if it does engage you could do damage to drivtrain, also if someone is under,in front of or behind the vehicle and engages " POSSIBLE DEATH or SEVERE INJURIES could occur. Be safe and good luck

It sounds like you need transmission fluid and filter change. This is one of the most overlooked maintenance items. It should be changed every 50k (30k if you tow a trailer) The delay in engaging gear is sign that trans fluid is tired or REALLY cold. In cold weather this is a normal symptom on cold morning starts but goes away when warm. I'd get it changed and soon, before it turns into a $$$ repair.

check the fuse first then check the solinoid on the front driveshaft to make sure it is engaging

you have a bad sensor check all sensors starting with air. berrydalewolf

solenoid switch that engages the 4WD more likely will need replacing. fairly cheap to fix replace.

you truly need to have it serviced and im sorry to have to say that however it could be a sensor or the transmission itself look for vacuum lines that may be rotted or a plug that had disconnected but this sounds like you need professional hands on repair

dont run it like that. have it towed to get fixed. or call a mobile mechanic.

it could be stabilizer bar bushings, or tie rod ends on steering linkage. It depends on your suspension set up. 2 wheel drive or 4 wheel drive?

Put it on jack stands. Start it up, put it in 4x4. Put it in drive. Both front and rear drive shafts should be spinning. Do they?