A faulty gas cap could cause the check engine light to come on but it would not cause a rough idle or engine noises. Start with having your local auto parts store read the codes. The codes will help determine why the check engine light is on.
Faulty engine
More than likely you have a tiny exhaust leak. Could also be a bad lifter but you would hear that at all ranges.
Could be, worn bearing/seal in water pump, loose hose clamp, faulty hose, faulty radiator, faulty gaskets, faulty heater core, faulty freeze plugs in engine block, faulty radiator cap, cracked cylinder head,
from which part of your engine is the ticking noise coming from. if is the TOP it would most likely be lifter noise.try using a thicker oil.
No an overheating engine will be due to leaking coolant, a faulty radiator, a faulty water pump, lack of oil or oil that needs to be changed
Engine is overheating, faulty gauge, faulty temp sensor......
Collapsed hydraulic valve lifter? Rocker arm (valves) need adjusting?
It is probably the lifters. I suggest using an engine flush and I have had luck with GUNK. Follow the directions on the can. You may have to do it every 30000 miles . I found that if I put a non Mitsubishi oil filter on my pu would start making that ticking sound
Its possible that this ticking sound is caused from driving fast for prolong periods. Its possible that its not the engine that is making the sound, but the exhaust system somewhere. I hear a ticking sound if I drive over 140KMh for long periods. It always stops once the car cools. I hopes this helps.
The engine overheating, or a faulty gasket, or problems with hot spots in the engine.
98 Chevy new 383 block 30k, ticking noise from sounds like heads . 210k on heads;
collapsed lifter?