Hi, Guys my mun's 99 4Runner has met some problem on shifting, the transmission gets stuck in neutral. I find some shift solenoids replacement on amazon, is that okay for me?

 

Generally when an auto trans does not move in a forward range, it's low on fluid or the clutches are slipping badly.
Occasionally, though uncommon, the front pump is bad. There are a couple others, but shift solenoids do not make the cut.
Put simply: go ahead, buy the solenoids; they won't fix the problem, unless the problem is a wallet that is too heavy.
Check the fluid. If it's ok, rebuild the transmission.

 

I think you're right, maybe I should check the fluid instead of change a solenoid.

 

The A340 is basically the same transmission as the AW4 that came in the Jeep Cherokee XJs so I do have some experience with them. They have 3 shift solenoids two of them control what gear it is in and the other is for converter lockup. When the two shift solenoids aren't powered or are bad it defaults to 4th gear which makes it not want to move in drive, however you can still manually shift it into 1st gear so you should try that first.