Losing power, jerking at lights, headlight/rear lights flickering

Car always had a chirping noise coming from somewhere in the motor compartment. No one can seem to find it or fix it. Then that progressed to where at idle it felt like something may be hitting something else and would produce a slight shudder only at idle. Neutral and park makes it go away. Still nothing to be found to fix. Now it progressed to where car acts like it is losing power, jerking at lights, headlight/rear light flickering only, nothing inside affected, RPMs remained normal. No codes have ever been thrown, so we are constantly chasing the issue blind. What is going on with my car? I want to fix whatever it is but no one can find it, I don’t have endless amounts of money playing guessing games. I just need to know because this is my daily, and only driver at this time. We change the oil/filters every 5,000 to 6,000 as recommended, recently had sparks put in. What next?