hey my moms 2006. 5.4l is having a motor miss at around 52mph going up hills, I’ve changed throttle bodies, recalibrated it, still same issue, took it to 2 local shops both say is functioning like it suppose to, no check engine light, but motor is missing at that 52mph . Is has 105k miles stock plugs and coil pacs
Any idea on what to change next
Any idea on what to change next