I will be going to go check out a "like new/very clean" jag next weekend and it may be my first Jaguar purchase. I'm curious if there's anything I should look for in particular or certain questions to ask. I know this is about a 30 year old car and being one of the last had made Jags I know there might be "issues" to look out for or little nuances to look out for in this year. if anyone or everyone can led there knowledge it will be appreciated.

 

sounds like you will be looking at a XJ40 also known as a "Series 4 XJ6".
(unless it is a Series 3 V12 which continued to be made until 1992 but only in 12 cylinders but it was not sold in the USA due to smog regulations.)

Basically the different "Series" defines the body style refinements from 1968 to 1987.

the Series 3 XJ6 was sold in the USA until 1987, then in 1988 the XJ40 arrived with a 4 liter engine, while the Series 1, 2, and 3 came with 4.2 liter engines.

ask in the XJ40 forum for better help.

https://www.jaguarforums.com/forum/xj40-xj81-25/