I have a 1993 ford escort with a manual transmission and 236,000 miles. I was on a trip yesterday when I slowed from about 45 mph to 10 mph to make a u-turn. When finishing the turn and starting to reaccelerate the rpms raced up to about 4000 and then fell back down to 2500. This happened twice very quickly and seemed, I thought, to coincide with my shifting . I thought I must be a real dufus with the clutch. Later in the day I was on the freeway going 70 mph up a small incline and the rpms suddenly raced up to 4000 for maybe 3 seconds and then fell back to 2500. I did not see a change in speed until after the rpms fell back to 2500. The change in speed was an increase of 1-2 mph. Is this a transmission problem, a clutch problem or something entirely different?
Sounds like your clutch is saying “adios”!
It may be the clutch shifting linkage is hanging …not letting the clutch re-engage quickly. You could do an engine stall test to determine how much friction the clutch faces have. A mechanic can check both.