hey people i live in washington i have a 1983 z28 with the lu5 305 in it. i had my motor rebuilt at bowtie proformance because the rings were going out ie 12 psi of vac. i put new vac lines in, replaces distributor, replaced tps, put all new seals in it, i cleaned the two iac valves, i replaced the coolant temp sensor, tbi gasket, cheaked all my bolts on manafold, retightened the valves and heads,changed alot out for new beacuse my car was idleing at about 3000-3500 rpms after i had changed the tps and coolant temp sensor it droped to about 1700-2100 rpms and it has 20 psi of vac still(ever since i rebuilt the engine) i am even pulled the computer out and cleaned all the conections + the prom. i am puling hair out beacuse it doesn't shutter when you give it gas no missing run's great just idels really high, i have to have brakes all the way down because stall converter stops at 1200 rpms so it wants to do 30 mph in gear and is not working right does anyone have any ideas, if you do thank you

 

@ IAC valves? I'm not familiar with an LU5.
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2 IAC valves?

 

yeah it has two iac valves simply put it just like a tbi just it's split down the center one injector on one side and another on the other side of the manifold. and it has hood flaps that are acuated by vac and a silonoid.
i found a vac diagram but i cant fig something out there is screw in valve near the back of the manifold that has two vac line connectors one on top of the other where does the two lines go
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iac intake air control it has a four wire connector

 

You should be able to look into the TB's and confirm the IAC is seated. If stuck wide open that yould explain a high idle. Or a significant vac leak. Is the upper plenum plate (gasket) properly sealed to manifold? Check that out.

 

i have gon threw all that but i think i might have a bad cam i looked and my intake and ex timing is only like 5 degrees diff

 

hey it's kyle i finaly found out what my problem was i had a bent intake valve on cylender # 8 and my intake manifold was cracked so i fixed it with jb weld and replaced a valce. it idles at about 600 to 750 and runs smooth the motor is up to having 50 miles on it