Symptom Checks

Check the following items:

Check the following Parameter Identification (PID) values: DPFEGR, ECT, IAC, LONGFT 1, LONGFT 2, VPWR and VREF. See appropriate article:

NOTE: On some vehicles, all PIDs may not be applicable.

On 4.6L and 5.4L models, check intake manifold tuning valve. Using scan tool, select IMTVF PID. PID value should indicate NO. Turn ignition on and note PID value. Start engine and raise engine speed to 3000 RPM. Again, note PID value. If either PID value indicates YES, go to CIRCUIT TEST HU, step 65) in appropriate article:

For 4.2L Pickup, see TESTS W/CODES - 4.2L .

For 4.6L Pickup, see TESTS W/CODES - 4.6L .

Check fuel delivery system. See CIRCUIT TEST HC in appropriate TESTS W/CODES article.
Check secondary ignition system. See CIRCUIT TEST JB in appropriate article:

For 4.2L Pickup, see TESTS W/CODES - 4.2L .

For 4.6L Pickup, see TESTS W/CODES - 4.6L .

Check exhaust system. See CIRCUIT TEST HF in appropriate TESTS W/CODES article.
Check engine compression. Check engine mechanical condition. Check intake manifold gasket, camshaft and valves.
On A/T vehicles, ensure transmission is functioning properly. If engine stalls during transmission engagement, check transmission solenoids. See TRANSMISSION SERVICE & REPAIR article.
Check for binding/dragging brakes.
On M/T vehicles, check clutch operation. On all vehicles, check charging system. Check customer driving habits (i.e., driving with excessive loads). If no problems are indicated, return to SYMPTOM DIAGNOSIS to identify any additional symptoms or go to CIRCUIT TEST Z in appropriate article and check for intermittent faults:

For 4.2L Pickup, see TESTS W/CODES - 4.2L .

For 4.6L Pickup, see TESTS W/CODES - 4.6L .