testing EGR solenoid, Sea Foam and O2 sensors

My freakin CEL came on again...code 43....Damn it I cleaned the bejesus out of the EGR as it was really gunked up. I cleaned the EGR temp sensor too. I already cleaned the Throttle Body. When I looked into the intake manifold with a flashlight there is a lot of carbon build up in there. I don't think I'm gonna pass emmissions so I might as well take the IM out and clean it in a tub of hot water and soap. I have cleaned internally an engine before with the Sea Foam treatment. I resurrected another car once and it didn't pass smog. After doing the treatment it passed emissions nicely. I feel like doing it on my Galant unless anyone here tells me otherwise.

Sorry to be a pain (like newbees usually are) but I have some questions for the Jedi concil

is the EGR solenoid a passive type unit? Meaning it is open while unpowered or should it be internally closed until powered by the PCM? that would restrict vacuum My guess is that it should be closed until powered. The reason I ask is because with the engine off, my hand held Mighty Vac reads no vacuum pull.....which means it's internally open when there is no power. Can I test it with 12 volts coming from the battery lead?

Another question is that is it true that a bad O2 sensor would not throw a CEL? I just wanted to know if I should just go ahead and replace both O2 sensors even if the PCM is not throwing out the codes for them to be bad. They were replaced back in 2005 or 2006 before being stowed away by the previous owner. They look aftermarket because they say BOSCH and look clean.

After cleaning the IM, you guys think Sea Foam would help clean valves and carbon build up to pass emissions? or is it a waste of time on these engines.


Car is a 94 LS, Runs great, minor tranny issues. It's completely stock and has been sitting for 5 years. Engine bay is clean and idles really good. Has no leaks and everything works. It was very well maintained by a local dealearship. Replaced down pipe and Cat. Will be doing T-belt soon after this CEL crisis is over.

sorry for the long story

Thanks guys....

and yes I know.....

I'm already looking for a 5 speed donor car.