My truck: 2001 Ford Ranger; 4x4 Off Road, 4.0L(Fl Inj.), Auto, 58,000 miles.
Problem: Truck shudders and stalls in reverse after engine is at operating temp. The same thing happens when transmission is manually placed in low. This problem exists in all drive modes.
How long has it been since it’s had a good, complete tuneup?
When the engine is cold it idles at a higher RPM. This may be masking a simple need for a tuneup. Plugs with too large a gap may not have the oomph to get it going from a dead start at lower RPMs.