If you had said it makes noise when you were at full-lock & kept trying to turn the wheel a little further, then I'd say check the PS belt for slipping.

Maybe the PS pump is going... Think you got your money's worth out of it? How does the fluid look? Maybe drain it & put in fresh PS fluid to see if that helps.

How about brakes? Usually the pad-wear tabs make a grinding or screetching sound (fingernails on a chalkboard). But one time mine made this noise kinda like moaning...

Spark plugs & air filter... Well, at 158k this can't be the first time you've ever done it. Measure the compression just for kicks while the plugs are out. Don't drop any debris down into the sparkplug holes... Let the engine get cold before putting in the new plugs, so you can get them out next time without resorting to explosives.