I have a 2003 F150 4X4 that I have had Transmission issues with. I had a blown head gasket so I ordered a rebuilt engine and also a rebuilt transmission. There was nothing wrong with my transmission but with 236000 miles on it I thought it would be a good idea to do so. I replaced all belts, hoses, radiator, heater core and everything I could think of so I wouldn't have to work on it for a while. The first transmission I got they left the filter out. I had to have a transmission place replace the transmission with another one from their company. The second transmission had to have the solenoids replaced inside the transmission. I had to pay the transmission place for removal and replacement of these units for warranty. I still had issues. The company sent me a different one from another rebuild company. I got it put in and it started having issues. I got mad and took it to the Ford Dealer. They found that during all the change outs there was some wires touching the exhaust pipe and needed to be repaired. They offer me the chance to repair them. I did and this transmission lasted for a trip from one end of Florida to the other and then it started acting up. I noticed that the overdrive switch never worked but you cold tell the transmission was going into high gear due to Tach. Well I was driving and noticed when I left a red light that it shifted funny. I went up a bridge and noticed the Tach going up and down showing me it was shifting when it should not. I got to the end of the bridge and pulled over. I did not have forward or reverse. I had it moved to me home. The next day I went to try it. It had all gears and moved. Still acted funny. I have found if you let it get warm and try to put drive off in reverse or forward it will not move. You can hear it make a funny noise. I have been carful not to burn the clutches. I replaced the speed sensor. Still won't go. Works when Cold! No Codes. Any suggestions what's wrong? I am going to take it to the dealer but I am going to try some things myself. Oh yea. I did replace the transmission cooler when I put in the first one. The transmission guy said he flushed everything each time he replaced them. Any good transmission service techs out there? I have a Gremlin in my truck ! HELP!!!

 

I also have a 2003 Fx4 with about 180k. I am starting to have some issues with the tranny, shifting hard, starting off hard. I kind of expect it to keep getting worse. In your case, if you bought rebuilt engine/tranny combos they should still be under warranty if you have an ASE certified mechanic install them. Take it back to them and have them diagnose the problem. It may be something like the transmission cooler or lack of flow in the cooler unit itself.

Good luck.

 

Yeah, I have a 2003 4x4 screw with 320k and no problems. I tow 3500 lb-5000 lb occasdionally They need to fix your transmission or replace it.

I change fluid and filter often..