Have you tried pulling diagnostic trouble codes? If it is in limp mode, there will be diagnostic trouble codes. Also, did you use the correct transmission fluid as well as filter and properly check level? The knocking in neutral has me confused. I'm not sure what was done that could have caused it.
I can't remember if the 1999 had a transmission dip stick to check level. If it does, great. If it doesn't, explain how fluid level was checked.
Let me know.
Sunday, November 17th, 2019 AT 7:08 PM