sluggish acceleration once over 30mph

let me guess its an automatic? i own a 2003 neon manual, the acceleration all the way till 80 is fast then it starts to slow down

The down shift cable pops off, the lever going into trans caused by the lever rusting, you can find it directly under the battery. Daughter had the same car with the same problem

Transmission fluid level might be low or the transmission filter may need replacing