i just wanted to know whats the best after market intake for my 305.what do i do with the air sensor once i put it on?

your question is a bit vague, which is probably why you haven't gotten any responses. Another reason is that topics like this have been covered many times, so you can usually find the answers your looking for by doing a search.

that said, I'm going to guess you're talking about the 1988 TA you list in your profile, thus a 305TPI. Unless you plan on a motor swap, a modded TPI intake works very well for most 305's. Do a search on porting the plenum and porting the base. Then possibly bolt-on a good set of aftermarket runners. You could buy an aftermarket base, but IMO, it's probably not worth the $ for a 305. If you're going to go that far, I'd look into the holley stealthram, but it is not 50 state legal, so it isn't the best option if you need to pass any emissions.

As for the "air sensor" I'm again going to guess that you have a TPI intake, thus you have a mass air sensor. This sensor must be re-used unless you change ecu's(computers).

Now, if you actually are talking about the "cold air intake" thus the air filter ducting, not the actual intake, there are VERY few aftermarket systems available. SLP I believe is the only one, most members tend to fabricate their own system. Once again, you will need the mass air meter inline between the filter and the throttle body for your car to run correctly.

I have a question too, i have a 305 in my 87 IROC and i have looked through so many websites to find an intake that will be the stock height, work with my stock rails and injectors and come with a freakin plenum. Is there a good priced intake setup that is basically like the stock intake but does better? cause ive looked and looked but found nothing.

Good question, but probably get more responses in the tpi section, and probably lots of options on what to get or modify

Look for the F.I.R.S.T. TPI injection system. Its a TPI but ALOT better and bigger...

Best? probably ITB.