Ford Repair: Sound like knocking, vacuum modulator, hr changes

Question
I have Ford 97, 77000 miles. Recently, I noticed that when I try to accelerate the car it goes up to 30 km/hr then changes to the second speed and at 55 km/hr changes to the third speed, after that I start to hear a sound coming from the car like knocking (almost between the engine and the gear) and the sound is even higher when changes to the forth speed at 80 km/hr.
I showed the car to many mechaics. One told me to repare the gear completely, another told that the car has some deposits on the valves and when it gets hot it ignites the fuel once injected before recieving spark from the ignitor, and third one told me to unload the car computer!

Could you please help me to identify this problem?
waiting for your reply.

Thanks

Answer
Hasan,

From what I can understand of your question, it sounds like you have a transmission problem if it is shifting when it is not supposed to. Also have someone check the vacuum modulator on the transmission. Hope this helps and good luck.


Ken