89 dodge fuel injection problem

looking at dodge truck with a fuel injection. guys says sometime it runs good and then it runs bad and runs rich. replaced alot of stuff. what goes bad in them.

1st check it for codes. there are a few things that will effect the running. Bad Map Sensor, Ox sensor, coolant temp sensor, injectors, Throttle Body temp sensor, dirty air cleaner, vacume leaks hall effect sensor, corroded wire connectorsfuel pressure diaphram ruptured..

wow alot of stuff to check on a rusty old ramcharger!

Check the air swithing solenoid(and the 2 others) on the firewall. Usually corroded or bad. If it fails it can direct oxygen from the air pump into the exhaust when it shouldn't. This causes a BAD rich symptom.

Good luck