Have had 3 places put my car on machine...All say rebuild transmission,ie slipping , gears not connecting properly..Then tonight a friend told that a friend of hers that works on transmissions, told her that a plug on top can sometimes make it read bad...is this true ??

You're looking at a major rebuild. There is no small fix for those symptoms

Needs a rebuild or replace with a refurb or go to junk yard. I would say replace the bands but it sounds like it's pretty toasted

if it started slipping in 4th then get a new car. The transmission is going out. 4th gear is connected to the clutch and you will need to replace the clutch and the transmission when it gets worse. It costs in upwards of 2,000 dollars to replace and or rebuild. Good Luck

Check your transmission fluid level. Add if it is low. Your Ranger may at some point need a transmission rebuild. This involves pulling the transmission from beneath the truck and replacing the individual gears. Rebuilds are needed when the gear teeth (the grooved serrated edge of a gear) begin to wear. When this happens the gears cannot engage completely and the transmission will begin to slip.

Check the fluid level first.
Run car for 15-20 minutes, then check fluid with ingine running in park or neutral. (set parking brake)

You must wipe the stick clean and reinsert it all the way and pull out again to get correct reading.

You will see the marks where the fluid should be. (top dot or line is full when hot)

If low, add the correct fluid. (Parts store will tell you which to use)

If the fluid is full or very near it, check the color. It should look like cherry juice. (transparent pinkish red)

If the fluid is very dark, brown, or even near black, you need a transmission flush.
Should run between $65-$130 at your local oil change place.

This can help if the internals of the transmission are not broken.

I had a 2002 elantra, and the flush fixed my issue.
A friend had the same issue on her 2001 elantra and she needed a rebuild.

Let me know what the end result is.

There is a point that a machine works and a point that it stops, you need a transmission rebuild.

First check the Automatic Transmission fluid for proper level and add as necessary. If the transmission slips in all gears, then the torque converter might be bad or worn out. If it slips in only 1 or 2 gears, the clutches may be worn out inside the transmission. A transmission rebuild is indicated in the latter situation. Make sure that the proper Transmission fluid is used as indicated in the manual or on the dipstick (if printed on it).

the transmission is failing, it is losing hydraulic pressure either from a failed pump or a defective seal inside the transmission, by now the clutches are fried as well, so a tear down and rebuild is the only thing to do to fix this.

you should have checked the transmission fluid first .change it if black as dirty fluid can give you a sticky solinoid in the gearbox

dear friend-the fact that your vehcl does not pick up speed tells me that it is slipping,there is a pressure lost in the gear box,you have to remove and rebuild as the clutches will be burnt.