High RPM's in your engine which can be caused by a bad idle control motor, low Transmission Fluid, or bad hydraulics in the transmission, or maybe a bad gear.
The increased idle when started is normal, all properly working cars that aren't ancient will do it. As far as the hard shift goes, your tranny.
check fluid in tranie....and LUCAS tranie lube
Odds are the clutch is in need of a adjustment or replacement.
Possibly low fluid.
It's either the transmission valve body or the nut on the input shaft (?) has come loose. My car was doing the same thing and it was the loose nut.
A bad transmission gear can cause your 1999 Nissan frontier to shift hard. Low transmission fluid can also cause the transmission to shift hard.
If you leave pizza in the sun it will go hard put it in the frige
Has recent work been performed?
How would you know about my car? Get literate! The friendly answer is worn engine mounts or to high idle speed.
Hey K==It will start grinding in reverse and hard to shift in foreward gears. GoodluckJoe
You didnt mention degree of difficulty so I'm going to with a general answer here. If it's hard to shift from park to reverse and you park at an angle on hill and you don't set the parking brake, then it'll be somewhat hard to get the car out of park. This is because you're taking off the transmission parking prawl with a degree of force when normally the brakes on the car should hold the car in place. Other than this you might have transmission problems. I have this problem on my manual transmission. Going from anything to reverse doesnt work, I have to shift it to reverse, hit the gas a little and let off the clutch a bit, and then pull the gear shifter back out and into reverse again.
The primary cause of a transmission to experience hard shifting is low fluid. Fluid is the life of a transmission and operates most of its functions.