1995 5.8l motor, 164,000 miles. A week ago was driving, came to a light and felt it idle poorly, it corrected and thought it was just some bad gas. Couple days goes by and it happened again at a light. Surged a little then cleared up. Then it started to happen a lot. Now its idle is very poor/misfiring and surging. I can go down the road and its fine, even sit at a light for 30 seconds before acting up. Doesn't matter if cold hot warmed up or anything. Also has an excessive intake sound when idle gets lumpy. The truck will stall out also. I've replaced the iac, checked vacuum leaks, new cap, rotor, plugs, wires, fuel filter, checked fuel pressure- normal, checked tps-functioning correctly, blocked egr, replaced all vacuum lines. The only thing that I've wondered is while doing an oil change the weekend before the first idle problem, a buddy of mines dad was over and we were talking about hesitstion issues with his truck and how he sprayed wd40 into his throttle body. Which he proceeded to do and me not the most intelligent thought it was ok. Wondering if there is a possibility that has something to do with it. I did take the throttle body off and cleaned it with throttle body cleaner. Also sea foamed the vacuum line from booster and used some in gas tank. Wondering what's causing this idle problem.

 

And also changed the 02 sensor.

Thanks in advance

 

Oh and also changed pcv valve