Help with 98 running rough
OK, on my 98 F-150 4x4 Super Cab, the problems started with a P0401, and the truck running rough. Replaced EGR and code went away. No trouble codes in 3k miles. Truck runs rough under slight load, but press on the gas and away she goes. Fuel pressure checks out fine. Plugs, wires, injectors, MAFS, TPS, and Fuel Pressure Regulator all replaced. Every step seems to offer only the slightest improvement. If I pull the vacuum line off of the fuel pressure regulator, there is no change in idle. I've applied separate vaccum to it, and still no change. Bottom line: I'm baffled. Any ideas out there?