Hello, I have a 1990 F-150 with a 5.0 and AOD. The truck was running fine for a very long time. The issue has been this, once you put the truck into gear from park or any forward or reverse gear the truck jumps and if you let off the brake it will go 15mph without giving it any gas. The RPM's is at 1200. When trying to slow down, I have to exert a lot of force on the brake pedal and the truck will dog down until 600 RPMs and then it will stop and then it will idle fine.

 

Something is wrong with the engine, not the transmission. Get the idle right and the trans will work right.

 

Thank you for the reply. I actually have been trying to get my idle smoothed out and hopefully this will help fix the situation. I was just hoping it wasn't a case with not having enough stall in the torque converter since the engine does have some internal mods.

 

I have got the truck idle very smooth. However still when the truck is put into gear it slams. It does so more when the truck warms up and driven. It shifts at the correct rpm's, however it feels as if the torque converter is locked up all the time. When it shifts from 1st to second and into drive the truck has little power until the rpms are above 3k or a higher speed just like shifting a manual transmission from 3rd to 5th. Could this possible the condition of a locked up torque converter or something else in the transmission? I am currently using TCI brand mercon V fluid.