I had a 2001 Ford Ranger 2.5 hard start either cold or hot once I get it started it has a rough idle and stalls if you turn the AC if I drive it once I get to about 3rd gear I can hear a pinging noise in the engine on acceleration I have replaced throttle position sensor, crankshaft position sensor ,idle air control sensor, plugs ,wires and coil packs. I have run Lucas fuel and Oil Treatment into engine treatment through the system hoping it would maybe fix it but nothing has worked any ideas at all would be gratefully appreciated.

Also if I cycle the key several time it will finally startand idle rough for a few seconds then idel ok till ac turned on then engine dies

 

Throwing parts at it is gonna be a shot in the dark in hopes of fixing this issue. God knows how many times i tried this before realizing it never fixed anything and i was only frustrating myself further. Thats where i began to understand how it all works by watching troubleshooting videos and watching the expert mechanics troubleshoot.

Suggest finding someone with a diagnostic scanner to tap in and see whats going on. Be careful of some of those new parts your installing if they are aftermarket branded, they can be so cheap that they cause other issues. Such as cheap idle air solenoids can cause idle issues.

Run the scan tool and see what (if any) codes pull up. Also check the live data while engine is running to see what the timing, fuel trims, and other stuff is doing. May need to bring to a professional for help on this.