tell me why today im on the highway going around 40 mph as i hit the brakes i notice and felt my rpms go up from 2-1/2 to 3-2/3 almost 4 and as i went faster it did the same thing but when i hit the gas the car moving. just last week i change the knock sensor and thats it what could be the problem.

also sometimes when im going at slow speeds ( in drive) the rpms will jump up almost 2000 to almost 4000 and when i hit the gas and nothing happens the car will act like its in neutrul sometimes i have to be careful, i be peeling out in traffic. guys i need help
my crankshaft sensor came up bad i will change this week, i dont think thats the problem. is it the tranny or maybe a sensor
ps i have a 95 max -gle- auto 140.000k
help please
thanks :

 

could be the tranny. i have a 5 spd, and i remember putting it on 4th gear, and it went in but rpm would just go up and no movement of the car.

 

start lookin for a 5spd, tranny is goin