2004 Ranger 3.0L low rpm misfires after warm-up
Hi, first I should say this truck has always had a slight rough idle. Took it back to dealer 3 times for this and the last time they told me Ford expert said it's normal for a 3.0L V6. Have always thought that to be BS. Truck has 115,000 miles on it now and becoming a real problem. Runs fine when cold but after warm up it will misfire at rpm lower that 1500. MIL codes are --random misfire--misfire on cyl 1--misfire on cyl 2--misfire on cyl 3. Can power brake at stops and all is good, but if I let it go below 1500 rpm will misfire almost every time. When it starts misfiring I have to go in neutral and rev engine, then cylinders kick in, put it drive and go. Or can turn engine off, restart and all's fine till I let it go below 1500 rpm again.
Have replaced plugs, plug wires, coil pack, fuel filter. Have cleaned injectors with fuel rail cleaning system, cleaned MAF sensor, Cleaned idle control valve, compression checks fine, TPS tests fine, fuel pressure checks fine, have swapped 02 sensors from bank 1 with bank 2 and problems remains on bank 1. This model year has no egr system.
I'm thinking maybe PCM bad, but that's money I don't have right now.
Can disconnect battery for 30 min, then reconnect and runs ok for a short time, as if the computer has to learn how to screw up.
Anyone have any ideas for me to check out, this thing is driving me nuts...