Bud I would try pressure testing the cylinders first before pulling the heads. I would hate to see you spend the money and the work involved without pressure treating them first but its totally your option. Grab a chiltins Manuel or Haynes from one of the parts stores for 25 bucks or less , they have nice illustrated instructions if you choose to go ahead with pulling the heads off.

I wanted to try to adjust the valves and I told my mechanic that it would be nice to do it before, but he said there's no way to adjust them, it's not a chevy where you can easily adjust the valves, so unless someone can explain step by step how to do it so I can do it myself( I'm a newbie) I don't want to take the heads off, and sorry, but I did not understood how to adjust the valves from the past posts  

Finished the job, adjusted the valves, cleaned the heads at the machine shop. Runs a lot better now, but got a CEL for:

 

P1507 No DTC Definition found

P0507 Idle air Control system Revolutions Per Minute Higher than Expected

 

Also, the gas pedal vibrating a lot pretty much all the time. RPM on parking around 1.2; on drive around 0.9

 

TPS sensor is good, just might need to be adjusted, and also we tried to adjust the gas pedal and cruise control cables. Any suggestions what should I do or how to properly adjust both of them?

 

Thank you!

Both codes are probably because your throttle and cruise cables are adjusted incorrectly.

 

 

The cable should be loose. It should be able to wiggle side to side about 1/8"-1/4" easily.

You have 2 nuts on the end of the cable sheath. One lock nut which is the closest to the throttle lever. The adjusting nut is on the other side of the bracket, towards the front of the car.

Loosen the lock nut, then spin the adjusting nut to adjust tension on the cable. If you spin the nut towards the lever, it pulls the cable tighter. Away from the lever will loosen the cable. Once you get it adjusted tighten the lock nut while holding the adjusting nut in place.