Help! My truck isn’t idles low and then stalls out.

[wonderwes2]

My 1987 gmc r1500 was idling very poorly and stalling out very fast. I just replaced the iac valve and now the truck idles extremely low for less than 30 seconds before stalling. If I touch the gas at all it revs super high but as soon as I’m off it it stalls again. I tested the injectors with a 9 volt battery and they seem to be working and the fuel pump primes so I’m unsure where to go from here. Any help would be great. Thanks.

 

[YakkoWarner]

Is you SES light funtional and if so, is it coming on to indicate an error condition? If its not showing an error thats not particularly surprising, I havn't found the error code system on these old OBD1 to be all that helpful (even if you do get an error code it is vague). Do you notice any lack of power when driving?

 

[wonderwes2]

The engine light is not coming on at all but it does have a huge lack of power when driving. I also pulled the spark plugs and noticed that only the drivers side is running rich (the left spark plug).

You must be registered for see images attach

 

[Ricko1966]

The engine light is not coming on at all but it does have a huge lack of power when driving. I also pulled the spark plugs and noticed that only the drivers side is running rich (the left spark plug).

You must be registered for see images attach

You need to find out why the check engine light isn't working and fix that 1st. You may have a power issue to the ECM a bad ECM a bad bulb. But that's where your trouble shooting needs to start. Because you will be able to pull codes a narrow down problems,and you may fix all your problems when you fix the check engine light, if the light problem is related to the ECM. Start simple check fuses and bulb 1st.