Hyundai Repair: Hyundai Sonata 2002, hyundai sonata 2002, transmission control module

Question
My Sonata 2002, started loosing power when driving. I was on the highway and out of nowhere it started to loose power then it would go again. It did this for about 70 miles when I returned home. While accelerating there was no problem, but when just cruising at one speed it would keep doing it. I was wondering if it was the fuel filter or fuel pump. Where is the fuel filter located? And is the fuel filter in the fuel tank and are there any precautions other than any other car when replacing the fuel pump? The car has 158,000 miles and I have never replaced either one of these.So I suspect one of these may be the problem.

Answer
It's doubtful this is caused by a fuel pump or filter or anything else that would cause a low fuel pressure problem.  Low fuel pressure manifests itself most when the most fuel is required, on acceleration.

I'd suspect perhaps a transmission problem or any number of intermittent problems.  Checking to see if there are any diagnostic trouble codes stored in either the engine or transmission control module will be a good place to start.  If your check engine lamp came on when this was occurring or is on now, there should be codes stored.  If there are codes present, the codes will tell us the nature of the problem.  AutoZone and AAMCO have advertised they'll check the codes for free.  If you follow-up with code numbers, I can tell you what they indicate and advise on diagnosis and/or repair.