I have a 88 4runner, 4 cylinder. About three weeks ago, i was doing 65 on the highway and my engine revved up for no reason. Didn't think much about it but about a week ago its become more consistent. As i shift into each gear the engine will rev up (after i release the clutch) and then accelerate. Acceleration has been much slower than before this issue started. A friend told me it's a sign my clutch is going bad. Thanks in advance.