When I first bought my van, the cat. converter was blocked, which I've read could have some negative effects on the EGR system. Occasionally, my van has a tough time starting (1 out of every 10 times, it runs real rough after startup until I rev the engine up for 15 seconds or so) and I can hear some piston slap when the engine is cold, but other than that, after getting the lifters replaced, it's been running great. I'm planning on replacing the TPS soon and cleaning the throttle body, so I'm wondering if I should also go ahead and replace the EGR valve and modulator. Does anyone have any recommendations on how to tell if this is necessary? Also, if I don't end up replacing them, is it a good idea to at least clean them up? Lastly, if I do decide to replace them, does anyone have a lead on a source? I haven't been able to find them anywhere online.