I have a 2001 Dodge Grand Caravan. With the car in gear, the speedometer jumps up and down and then finally stops dead at the pin past 130 mph. There is often a "bogging" of the engine when I take of from a red light as the speedometer is going crazy. I took it to a mechanic who replaced the cluster. The fix lasted about 6 days and it is now back to the original symptoms. Any thoughts?

Caravans can have issues with the sodering on the guage cluster boards. If you can't solder you may need to replace that part.

check your ground wires

Some cars have gauge fluid that has to be refilled.

try to remove the cluster and check the back connectoer on the cluster. I have had problems there. you will see the termanls open

The speedometer is operated by a cable to the transmission. The gear selector is also a manual linkage. Neither are electronic. There may be something stuck underneath inferring with them directly.

no codes found because your checking the PCM,
your problem is you need codes from the TCM,the computer for the transmission,since you replaced the speed sensor the other two things that affect a speedometer and transmission are the input and output sensors,they both screw in the transmission.

you need to take this to dealer for repairs,there might be a short in the speed sensor wires that did that to your speedometer,the reason it won't shift is speed sensor,input sensor or output sensor on transmission.

These vans have had issues with the PIN connections to the instrument clusters. With time the solder on the main PIN connection will begin to fail. The good news this may be repaired at home. First you'll need to remove the instruments. To do so remove the dash components from around the instruments then the (4) screws) that hold the instruments in place. Carefully detach the wire connection from the back of it; take to a well lit area. Look for a PIN with a failed solder joint (this will appear as a slight black or grey circle. If found apply heat and let solder be gin to flow; the allow to cool and reassemble. If you look at my history you'll see I've helped others with this issue. The attached link may help: http://dodgeforum.com/forum/dodge-caravan/197192-99-grand-caravan-intermittent-dead-dashboard.html
Please let me know if this assisted you,
Tom

Hold down the black plastic TRIP METER RESET switch for 10 sec and ti will go into diagnostic mode. I did this and its cool. Do it with the van turned off!

sound like the vechicle speed sensor.