fuel injector a spark plugs

been reading a lot and for the fuel injectors I see a lot for the renix system(which I do not have) and I have a 97' 4.0l, so I'm kinda wondering what a good fuel injector pieces would be good to replace the ones I have(its at 191K miles) and I'm also confused on spark plugs, Ive read that champion is best but then again I saw some saying theyre good for mowers?? and that ngk are for 00'-01' but some have use them in older models. which of the two is better and what which one at that since I think each company makes a few different kind

NGKs work well in all the 4.0s. All I use.

www.precisionautoinjectors.com can help you with injectors.

But, with a 97, I'd get me a can of BG 44K and add it to a full tank of gas and run it. That stuff is amazing.

Check out this thread on which spark plugs to use. Lots 'o good info. Bare w/ me as I'm not sure how to quote from another thread into this reply. Here goes, fingers crossed.

http://www.naxja.org/forum/showthread.php?t=1086094&page=3