My 86 305 was idling fine a few days ago, then all of a sudden it dropped about 150 RPM's. I checked the PCV valve (by rattling it) and grommet (I replaced it), I believe my EGR valve is OK but not sure (how do you check that?, the vacuum to it is good), I believe my TVS is good but did not get any vacuum/pressure (I do not know which one) to/from my carbuerator (should there have been)? I checked the fuel vapor canister line which leads to my TVS and there was no pressure there, should there be? I am banging my head against the wall becuse I have checked all of my vacuum lines a bunch of times and still can not figure it out. Is it something as easy as turning up my idle, I counted that one out because it does not make sense for the idle to change that much in one fail swoop.