1995 Tacoma with 2.7 EFI engine has high idle speed. When cranked cold idles at 800 rpm but as it warms up idle speed increases up around 1600 rpm. Does not idle down when clutch is fanned, have checked for vacuum leaks and have also checked most sensors. The exhaust manifold is cracked and I am not sure if this might be part of the problem. I am not convinced issue is not vacuum related but not sure of a definite way to resolve this question or issue, Any suggestions??