Hi, I'm a new member with an 89 F250 5.8 I use for a work truck. Had an occasional high idle and took it to a shop who couldn't find a problem . They cleaned IAC, check timing, TPS, scoped and code checked it. Nothing wrong but I still got the sometimes high idle. I replaced the IAC and now it stalls on warm starts. Idles rough and high hydrocarbons on smog test. It did have a 33 code for EGR. I replaced the EGR and sensor but as far as I can tell the EGR never opens under any conditions. No vacuum ever to it. Tried another IAC with same result. When I remove it and energize it there is no plunger movement with 12 volts at the connector. Is that normal? Does engine have to actually be running for it to open?