Howdy! My truck stalls either when I'm slowing down or idling. It seems to only do it when it's warmed up. I have a check engine light that pops up occasionally, but it goes away before I even get a chance to hook a scan tool up to it. OBD1. Here are all the parts I have replaced so far.
Spark plugs
Spark plug wires
Coil pack
O2 sensors
Fuel pressure regulator
Throttle position sensor
Idle air control
Maf sensor
Crankshaft position sensor
Fuel injectors
Fuel pump
Fuel filter
Any advice is appreciated. Help!
I have a check engine light that pops up occasionally, but it goes away before I even get a chance to hook a scan tool up to it.
You can access OBDI codes without a scan tool. Solving the problem that prompted the light to come on can be a lot more difficult than with OBD II, since the data is nowhere near as detailed.
As an example, I had a very nasty vacuum leak on my OBDI BMW 540i almost 10 years ago. It was in the CCV valve assembly, and it would suck raw oil out of the sump and burn it. It looked like the car John Candy drives as Uncle Buck. When I'd start it up, it would smokescreen. A friend of mine who knew cars better than me at the time, came out and sprayed starter fluid around the back of the engine. Vacuum leak. I replaced the CCV valve assembly. The light didn't go out for 45 minutes or so, then it went out, and the oil stopped burning. Firestone was going to just replace the 02 sensors and charge $500.
To get information out of an OBDI vehicle, there's typically some functionality built into the car to access the code. In my BMW, you turned the key to run, without starting the car, then fully pumped the gas to the floor 5x. The check engine light flashes rapidly, pauses, then rapidly to indicate a code. You need to count the flashes. Say it's some random number, 531. It will flash 5 times in rapid succession, pause, flash 3 times in rapid succession, then flash once.
Here's a list of Ford codes and their meanings in the Ranger: OBD-I Diagnostic Trouble Code - Ford 3-Digit Codes - The Ranger Station
(19) How to check Ford OBD1 trouble codes without a scan tool - YouTube
Given how old your truck is, and that this issue is intermittent, you may have an intermittent vacuum leak as well. Slowing down, getting hot, etc. moves hoses around and they can open if they're cracked. If it's still got the original hoses, I would start replacing them all, 1 at a time so you don't lose track of where they go. This is the simplest thing to do first. Those vacuum lines are pushing 30 years old.
A very long and detailed reply. Thank you very much. 