Hi 1998 Mazda B4000 4.0 I bought this truck and it would hesitate at times and miss around 2000 rpms on street or hi-way. Checked Pc, Iac, Egr, Tpc, Maf sensors, and all were working. This issue did not have a error code. I found that I had a Ground problem ( Low Voltage at the fuel pump ) After cleaning the grounds (next to dr side kick panel behind the cover There is a ground connection ) also the Fuel pump connection under the truck (using electrical cleaner) So far I have not experienced any more problems. PLEASE CHECK THE SIMPLE THINS FIRST DIRTY OR BAD OR LOOSE CONNECTIONS B-4 GOING OUT AND SPEND A LOT OF MONEY. IHope this helped some of you that may be having similar problems.

 

Go to a Ford Ranger forum, that's really what your truck is.

I'd change spark plugs, air cleaner, fuel filter, start with that. Clean all your electrical connections too.