any ideas?4x4 and speed problems

hey i was wondering if anybody has any ideas why the 4x4 in a 95 jimmy doesnt work if the wheels lock out when you push the button.i know they are locked in i can feel the wheel getting stiff but i know the front wheels arent turning.i had the tranny rebuilt about 2 months ago and went mudding the other nite got stuck and my front wheels werent turning.i was wonder what would cause that.and also if anyone knows about if your crusing at a steady speed when i let off the gas my rpm goes up about 1 or 200 rpm before going down.it also seems to go down alot faster than usual.it also has no power and to pickup speed i have to down shift it, then it wont shift back until i let off the gas.thanks for the info

If you're sure the front axles are locked in, power is not being transferred to the front differential. Power is taken from the transmission output shaft and directed through the transfer case to the front driveshaft and sent to the front differential. The front differential is "live" all the time. The front hubs are splined to the axle shafts and are turning any time the vehicle is moving, independently from the front differential. When you "shift" into 4WD, an actuator engages a pin in the front axle housing and mechanically locks the axles to the differential. Check the operation of these things and you'll find the problem.

Regarding RPM increase letting off the gas: That is the lockup torque converter disengaging, and is normal operation. It unlocks for several reasons: #1 It increases available engine vacuum to the brake booster anticipating a stop. #2 To help slow the vehicle more quickly. #3 It increases engine RPM in anticipation of the next throttle application when more engine torque is necessary, higher RPM, more available torque.

Concerning the lack of power: Is the "Service Engine Soon" light on? If so, what codes are stored? Need more information to attempt a diagnosis on this.

there is no engine code.thats why im having the problems.i think its a vacume leak but i dont know for sure.i just know it has a major lack of power and i dont know why.

How many miles are on the vehicle? What's been done to the vehicle as far as repairs? How long has it been since it was last tuned up? What was replaced during the tune up? Have you checked the fuel pressure, if so, what is it? Is the operating temperature within range and approximately what is it? Describe the symptoms in detail. Anything that you can tell us will help and the more details you give us, the quicker, easier and more accurate the diagnosis will be.

the temp and oil are fine. it s about 14-15 volts runing.its got about 140,000 miles ive put new trany in january.well rebuild.i put a new egr valve and cpi last summer.and a tune up just after i got it.that was last spring and i put new plugs, wires, rotor and cap.i also put a new muffler on it in the fall.i think its got a vacume leak at the intake when i changed the cpi.but thats not why the 4x4 isnt working.thats just why it has no power.also in the fall i had given it a tranny flush,so the whole system was flushed.would a pluged cat cause this?

Depending on how restricted the catalytic converter is, symptoms can range anywhere from a slight hesitation on acceleration, to the point of full throttle barely moves the vehicle. It is possible for a converter to be so restricted that the engine will not start. An absolutely 100% accurate diagnosis includes removing the exhaust pipes from the manifolds, start the engine and analyze performance.

okay well im not for sure if thats it then cause it runs good for about the first few minutes then as it warms up it starts to lose power so im thinking its not the cat.i dont think it would vary as the motor warms up?i might try to replace it and iff that dont work im gonna take it to the local dealership to have it diagnosed.i'll just fizx it myself.thanks for the help guys.i was told to check the solenoid for the 4x4.i had been told that theyre known for going out.