Just checked and there seems to be no indication of a vacuum leak. I don’t know if it will help, but there is a very strong gasoline smell that comes from the exhaust and a little bit from the engine bay when the motor is running.Just to start:
Be sure battery terminals are tight.
Check the main air intake tube from the air filter to the throttle body. They tend to crack at this age and create all sorts of issues. Very common and easy to check.
Looks like this:
Look for any major vacuum leaks - did a hose pop off the top of the engine or throttle body?
Thanks for that, will definitely give it a try the next opportunity I get.If your battery terminals are clean and tight and your satisfied you don't have vacuum leaks it is possible the fuel pump relay points are worn. New FP Relay and save the old for a spare is the best bet but you can burnish the points on the relay as well. There are threads on this in this forum.
Mudders This thread will walk you through the procedure for removing, opening and cleaning the contacts on the Fuel Pump Relay on the 80 truck. After reading thru RT issues in chasing down some hard starting, I decided that after 145k, it was time to clean the contacts on the Fuel Pump Relay...forum.ih8mud.com
The engine does this all the time every 5 minutes or so. I changed the oil awhile back, maybe 300 miles ago. As for deep water, not really, I hit a big puddle every now and again since it’s been raining a lot lately. As for under the hood, I recently replaced the starter as it was going bad.Ditto: Does the engine do this all the time, rarely, every five minutes, only when cold, or only hot, or??
Did you do anything different before the symptoms began; washed the engine, driven through deep water, fiddled with anythng under the hood, get gasoline at a new station, --- ??
Will certainly give this a shot when I get a weekend. currently working 7/12’s, hardly any time to work on it at all.I had the exact same issue, went through all the FSM checks and finally found the egr valve was stuck In the open position.
An easy test is to remove both vacuum lines at the top tee fitting coming off the valve shown in the photo. Place a finger on one side, and use an air nozzle to get 10-15psi on the other inlet. If it is a stuck valve, this will force it closed, and the rough idle will go away immediately.
View attachment 2512280 delete threads are a good option if this is the case.