Starts great cold. After warmed up, restarts very hard, with bucking.
Fuel pump/sending unit replaced in 03 after being stranded three times. After that truck drove fine every day up till 07 when I got a new van (daily vehicle)
Truck sits a lot now, maybe driven seven times a month.
o2 sensor replaced three days ago. No change. Still fires up instantly in the morning, but after making a few stops during the day ie: store, bank, etc. It cranks but needs the gas pedal pumped a couple times, then starts and runs at very low rpm and bucks almost at the point of stalling. Within a minute it climbs back up and runs normal.
I have been running a higher octane gas as well.
Another fuel pump assembly?
Never had a complete tune-up. original spark plugs
Fuel filter was changed last year.
Semi-mechanical here (carpenter)