passing gear/transmission problem

Alright, this has been happening for a while but now it is starting to get bad. I have a 95 Toyota 4Runner, drop tailgate, 137, 959 miles. Sometimes when I put the peddle to the floor and the overdrive or passing gear kicks in, but I don't go any faster. It kicks up to higher rpms, but I still run like I am in lower rpms. Tonight was really bad. When I went to work I could barely get it up to 50 mph to get on the interstate. That makes it really hard to get onto a 65 mph interstate. The whole way I was having trouble keeping it at 70 mph. I would try to pass a car and it would kick up to 4500 rpms but it would run just like 3000 rpms. It even makes the sound like it is running harder, but it doesn't go any faster. I thought maybe it was just me but it really got me on the way home. A hill by my house is kind of steep. I can normally take it at 45 mph easily, but tonight I couldn't get past 30 mph going up it. Then I knew something was wrong. If anyone has any ideas of what is wrong, thanks for any help. Also if I said anything wrong just try to figure out what I am trying to say, sorry but I am a newb at this automotive stuff. Thanks again.

Could be a tranny problem, or a clogged up cat conv.

I had a Cherokee XJ (manual) and power was fine until I started up hill.
Needed 3rd were before 5th would do it. Clogged conv was killing it.

it sounds like the tranny might be slipping a little bit. it happened to my sisters dodge, after a while it wouldnt even move forward, only move in reverse.

my 1992 4RUNNER has the same problem as you describ it and sometime the truck will not move forward on 'D' or '2' and then the O/D OFF light is blinking and yes uphill I can only do around 35 to 40 MPH, they told me it could be the TPS or MAS sensor, right now I am trying to adjust the trottle to see if it can get a better RPM, try this, get your jack and lift the back rear until both of your tire will lift off from the ground then use some wood or anything to put under your front tire so if it will not move while you are diong it, after you done that, turn your car on and set it on 'D' and press the gas, if it does the same then open up your hood and try the inside trottle and press it, if it is diffrent from the inside gas pedal then I think you need to adjust the trottle line or a new TPS, when diong this always stop the tire when you are switching the gear or you will hear grinding... and always prepare to press the brake pedal incase the jack fall off... second is mayby your transmission filter may need clean or change, and also check the injector..., and solenoid inside the trans..