93 sidekick 16 valve MPI. had a horrible miss at idle once engine warmed up but only on number 3 cylinder. Did plugs, wires, cap, what not cleaned EGR valve. Finally replaced EGR valve and now idles great but miss moved up the RPM range to 2000-3000. Capped vacuum line to EGR and runs fine. I found out the exhaust gas is routed to each intake port and assume I had two problems. First EGR bad and leaking (new one fixed that idle problem) but the reason it only affected #3 cylinder is other ports plugged causing #3 to lean out. So now the EGR is working properly it is leaning out #3 at 2000-3000. Haven't tore the intake down just running without EGR. Does anyone know how to orientate the EGR modulator cap? took mine apart before checking.

I have seen this problem on Ford 3.8 v6 series engines with egr ports for each cylinder. The individual cylinder ports get plugged usually leaving one open then when the valve opens all the flow goes to 1 cylinder causing a mifire due to low O2 levels in cyl. ck and make sure they are all clean all the way to the egr valve in intake.