2002 Hyundai Sonata mass airflow sensor didn't work

2002 4cyl Sonata wouldn't start. Thought had frozen fuel line. Son in law hooked up his diag computer and said was faulty mass airflow sensor. Towed to non dealer shop, where they replaced it with dealer part MAF. Two days later went to pick up just as they were closing. Wife drove home. When she mentioned she could hardly get up hill several miles from home, I repeated the drive and found she was right. Plus, I thought she must have had back window down as I heard strange background noise. Car would barely make it up hill. Next morning wouldn't even start. Towed again to repair shop. They were stymied. They held it for several days and then gave up and advised us to take to dealer. Said that it was running but was sluggish. They set it out overnight. Once again wouldn't start that morning for me when I got there. Could it be faulty installation? What about air filter? I recall my son in law spraying carb cleaner(?) Around air filter on first night. Aren't there oxygen sensors? But wouldn't that show up on diag computer? Repair shop said everything checked out as kosher.