I hoping there is someone who would be able to help me figure out what’s going on with my new purchase a 97 Gt 4.6 2v. The car makes a somewhat loud ticking noise in and around 2,000 RPM but comes and goes?? If i shift the car at approximately 1,800 RPM or less the car won’t make any noise at all and if revved over 2,000-2,200 the noise goes away? after rattling/ticking. Also if I put on the defroster on the car will surge up and down in RPM and will hesitate but still run quite well?. The car has 125,000 km on it and runs great with no check engine lights and no other problems. Any help would be FANTASTIC!!! Also how much work and what tools are needed to remove the head from this year’s engine?