I am in Galveston, Texas, and I'm looking for some advice on my '94 4Runner. It used to be my daily driver, but one day after leaving work, it suddenly lost power as if someone flipped a switch. Now it will only reach 40 mph, and it takes a while to get up to speed. All cylinders are at 160 psi compression except for one, which is at 155 psi. I've installed new plugs, wires, and a distributor. Additionally, there's a new sound that started, similar to a loose belt whining.that started when ever whatever flipped the switcha

 

it also has a new clutch assembly its not slipping or reving up it did show a code 12
and it idles like a sewing machine i do not suspect head gasket

 

Which engine? Put a timing light on it to make sure the engine did not jump timing.

 

3.0 everything is in time

 

a timing light won't tell you if both cams are in time with the crank. or if the harmonic balancer is coming apart and the timing mark is walking around.
pull the timing covers and line up the marks like shown in the service manual.