Hesitation - 2001 Expedition XLT (5.4L)
Purchased used 01 Expedition 3 weeks ago. I've added 760 miles to the original 112k. I felt some hesitation on Sunday (hwy speed, uphill) which caused a few jerks. It evened out after cresting the hill and we arrived home without further incident.
Monday evening, heading home... again at hwy speed (60-65 mph)... sudden hesitation with four or five big jerks. I'd classify it as four or five "misses.” We were on a slight incline, not much of a hill, but the engine was under stress. I was pulling around 2-2.5k rpm when the first big jerk hit.
Again, after cresting the hill it evened out. This happened again (twice more) before I got home, although not nearly as bad. Could feel the hesitation in the accelerator, but no jerks (misses). No "Service Engine Soon" light. I thought maybe water in the fuel?
This morning (Wednesday), driving to work... straight hwy, no hills...
Whammo! Jerking so bad, big-time misses. Immediate Speed / power drop. "Service Engine Soon" lamp flashing for all it was worth. Came off the throttle and pulled over right away. As soon as I came off the gas, it smoothed right out. I popped the hood (which exhausted almost everything I know about engines). My son and I remarked on how clean everything looked ("Wow, look at the shiny thing with "Ford" written on it").
It idled fine, no unusual sounds. No missing at idle. Checked inside and the "Service Engine Soon" lamp was off. We got back in and drove the 2 miles to my kid's school and work. Ran beautifully at 50mph, not one bump. It now sits in the parking lot, haven't made the first payment.
Any ideas on just what the heck I'm facing? Just wanted some info so I could at least give the mechanic a thorough report when I take it into the shop.
Appreciate the advice.