hesitatinon and stalling

[Milton Kirkland]

I have a 1991 ford explorer 4wd,at,4.0v6.The truck will be running fine at highway speeds and all of a sudden the tach. will jump from about 1700 to 2000 rpm.The engine will begin to ping.If I have to drive a long stretch, the problem corrects itself,but if I have to stop while the truck is acting up,it may stall.If it does'nt stall, it will hesitate upon applying the accelerator.Computer diagnostics shows no problems,so I have had to resort to a trial and error approach to the problem.I have changed the fuel filter,added fuel additive,replaced fuel pressure regulator,cleaned the injectors,replaced plugs,wires,TB sensor,MAF sensor,O2 sensor,CAT.,and torque converter solenoid.Still having problems.Any help is greatly appreciated.Thanks Milton

 

[Ira]

Check the torque on your intake manifold. Also, pull your plugs one by one and see how they look. If you have a leak in your intake manifold (common problem with earlier models), it could cause the pinging, rough running etc. Here is a link with more info. Dead Link Removed