High Rough Idle all the time Help!

[Hodges87]

I have a 90 Chevy C1500 5.7L TBI

When I start the truck it idles up and has a vibration in the motor. When its in drive with the brake held it idles normal but with a slight vibration. I replaced the cap, rotor, plugs (gap set to .035), wires, fuel pump, cleaned the IAC and reset it, sprayed carb cleaner all around the vacuum lines and TBI base, checked the egr, all to no avail.

Any help will be appreciated

Thanks,
Hodges87

 

[SAATR]

How does it run otherwise? Any misfires or surging on the highway? It sounds like a vacuum leak, and it seems like you've tried to run it down with no luck.

 

[Dubya]

have you tried cleaning your mass airflow sensor?

 

[Hodges87]

It runs pretty good on the highway, I can't feel the vibration at higher speeds. I very new to the TBI motors, I didn't know the TBI has a mass airflow sensor. Where is located and I'll clean it?

 

[Dubya]

no mass air flow sensor on the TBI motors. i was looking at the truck on your sig ha

 

[CJ91C1500]

any fix im having a simular problem