1990 mustang issues

[Ruffneck1320]

Ok, so heres the deal

Traded my bike for a 1990 mustang, with a 306 motor edelbrock heads and cam.Holley upper and lower intake.
When we made the trade i drove from garland to fort worth with no issues.
Now, the idle is really jumpy, she will go from 500-900 rpms, and she dies.
It is worse when the motor is cold, she will start up then immediately die. When the motor warms up the idle calms down a little, but is still jumpy and still dies after about three minutes at idle.
I had to drive it this morning to go get a part for my cummins (my daily, that the slave cylinder went out in last night) and she would die as soon as i took the car out of gear to stop. (5spd)

We have adjusted the fuel pressure to 40 psi, and adjusted the timing, i currently am cleaning out the iac with carb cleaner and going to try that.
Any other ideas would help out alot

sorry for the long read

[Coupe81]

Vacuum leaks possibly a cracked vacuum hose.

[91CoupeMike]

Check vac leaks and the Iacv.

The problem lies there.

[Ruffneck1320]

Cleaned the iac, now the car doesnt die, but the idle jumps anywhere from 1000-1500
idle doesn't go lower than 1000
Checking the vacuum hoses now

[Ruffneck1320]

lol now the idle stays at 1500

[91CoupeMike]

Cleaned the iac, now the car doesnt die, but the idle jumps anywhere from 1000-1500
idle doesn't go lower than 1000
Checking the vacuum hoses now

Unplug the Iacv and adjust the throttle stop screw.

Get it to idle at 500-600 and plug te Iacv back in.

Un do battery and while it sits unhooked check for leaks and also check tps voltage or just fiddle with it

[zemog]

take apart the mass air connection and clean it, also spray the mass air with ,mass air cleaner (can get it at any auto store), make sure the connection is good.

[Ruffneck1320]

Unplug the Iacv and adjust the throttle stop screw.

Get it to idle at 500-600 and plug te Iacv back in.

Un do battery and while it sits unhooked check for leaks and also check tps voltage or just fiddle with it

cannot get the car to stay alive at 500-600 with the iacv unplugged
i got it to idle at 800 plugged in and as soon as i unplugged the iacv she went died
i replaced some vacuum hoses that were very needing of being replaced
checked tps and mass air both good

[91CoupeMike]

It SHOULD idle with no Iacv, just low.

Seafoam it/

[JBANKS]

iacv IF THE SPRING IS BROKEN INSIDE...WON'T WORK...the spring in there makes it go up and down to adjust fuel to air ratio...if not that could be the Throttle Position Sensor

[garycrist]

Run a KOEO and KOER test too!

[CRASH]

Check the TPS voltage. It should be .92-.98 volts, with the key in the ON position. Which throttle body is on it ? Paul (greenbullitt) had to drill a small hole in the blade on my throttle body for a bypass.

Also, like mentioned above, check for any vacuum leaks. Mine had one on the underside of the boot going from the mass air meter to the throttle body. Just a tiny hole was all it took. Also had one where the oil cap screws on. There is supposed to be a small o-ring seal in the cap. One more to look for is the hose that goes from the throttle body to the valve cover. I'd be willing to bet you've got a vacuum leak somewhere and that's your problem.

What did you set the timing at ? You did pull the spout out when you set the timing, right ?

-Aaron

[Ruffneck1320]

Got it heading my way now
Roommate came home and found where the vacuum leak was.
Between the upper and lower on the intake
Yanked the upper off and replaced some bolts problem solved.
Tps was at 1.01
Its an edelbrock bbk 70mm throttle body
Replaced iacv with one he had laying around, that made alot of difference

Thanks for all the advice...I really appreciate it

[CRASH]

Good deal. Glad you got it figured out. Sometimes some of the most aggravating things are the smallest, most overlooked.

-Aaron

[JBANKS]

I agree!!! Thanks for letting us know! And in the IACV is that spring, tricky SOB IT CAN BE lol