'98 ZX2 engine chirping noise, belt? NO!
My daughter's (new to us) 98 ZX2 came with a chirping noise. I assumed belt tensioner or the infamous timing belt. After much searching on various forums, I found it was not belt related at all.
It is the round crankcase breather filter, part number FA-1661. Gets clogged and the back pressure makes it wheeze with a high pitched squeal.
To verify, just start the car, wait a minute for the squeal, then remove the oil filler cap. If the noise goes away, that's your problem.
Only Ford or on-line supppliers carry the filter. Takes 15 seconds to replace. My dealer had it for $19. Rock Auto had it for $11.
Hope this helps someone else!