Hey guys i have a gs400 i picked up not too long ago. And its recently picked up a small hiccup when cruising at highway speed sometimes and right when you start to go up a hill at cruising speed. Drives fine at lower speeds and at wot but only hiccups while cruising at hwy speeds and once creeping up on the slight inclines. I just replaced the plugs and they were all properly gapped which i hoped would have solved the issue. Also replaced the maf. Im kinda now leaning toward fuel pump and fuel filter but trying to get to info from the gang on if anyone has had a similar issue. Car just hit 187k so thinking could be the pump if it is the original but not for sure . Thoughts?

 

Sounds about right for the fuel pump. Mine went out around 200k coming back from the beach. I had the cruise on for an hour and the car just quit...I pulled over and it started right back up. Took it to the dealer the next day and a fuel pressure test confirmed it was the pump.

You really start to see symptoms when the tank is low and / or you're going uphill.

 

This is a common symptom of a coil pack going out too, might check for codes.