Hi, I have a problem that just started occuring lately. I previously had no muffler on my 88 F250 351w, just straight out cats. So I put a 2.5" pipe and connected it to the tailpipe. And it seems now when the engine gets hot, it feels sluggish, and when I stop the engine idle is very high for about a minute. It will eventually idle down but somehow I think the two are related. Only code I get is 33, the EGR not opening, which I had before this. I imagine that is part of it, running rich, but I wonder if the O2 sensor is weak or the TPS might be weak also. When it's cold the engine starts up fine, goes immediately to high idle, then drops within about 10 seconds. I also notice when this occurs, my temp creeps up just a bit, and my oil pressure goes to about 3/4 of the way up. Maybe I should put in a 180 temp thermostat, or my temp sender is faulty? Anyone every experience something similar?

 

BTW, I also noticed that this pipe I put in is already a dark blue color.

 

I think I might know what's up now. After reading my manual and testing the EVP, the ohms were low around 500, indicating the EGR is stuck open I believe. And this is with the engine off. According to the manual it should read around 5000 ohms when the EGR is closed which it should be with the engine off.