I was having throttle issues that was causing the throttle to hang up in the rpm. We'll i drilled my tb out to 1/4 inch and that was what was causing it. OK so i j b welded it shut and that fixed it , but know i think it need alittle whole there what size should i go with . I have a 643 598 lift cam 232 234 duration .
I have also noticed now that the map sensor is reading very low at idle and it i bump the gas it jumps up then go to about where is should be . So i cant be getting enough air at idle . Should i drill it or just adjust it open alittle.

With that size cam what should my map sensor be seeing as far as normal reading at idle.

Also would all of this have any thing to do with the fact that it buck frm 1400 rpm to 1900 rpms ?

 

no input?

 

You need to start w a 1/8" drill bit and drill one size larger until the IAC counts are at 30 or below while idling in park/neutral. This requires that you have a scanner that can read engine data. The surging is in the tune, but may improve slightly if you get the IAC down where it needs to be.

 

Drilling is a hack around a poor tune. Go back to the stock hole size (don't recall off the top of my head) and find a tuner who know what they're doing. Jimmy is on the right track.

 

There is no reason to drill the throttle plate. If you need some extra air for idle or low speeds. Use the throttle place adjustment screw.