96 Windstar 3.8 Ltr. eng. codes 1537/1538

[gasmith46]

96 Windstar. Both codes 1537 & 1538 in at the same time. They are not there all of the time. I can erase them and they will not show up again for a few days. The vehicle starts to run rough at idle in or out of gear and than check eng. lite will come on giving codes 1537/1538. Does not happen all of the time. I have replaced the frt. intake manifold runner control actuator already because the code at that time was 1538. Now I have this problem. Any suggestions?

[wiswind]

One way that these fail is that 1 actuator develops a leak, robbing both of the vaccum needed to operate.
You could check to make sure that the vaccum lines are securely connected.

Also, you could remove the vaccum line from one actuator, place your finger over the vaccum line and see if the other actuator pulls in.
If it does, then the one you have disconnected, is the defective one.

As the problem seems to come and go, it could be tough to track down, as the diagnosis will only work while the failure to pull them in is present.

Another thing to check would be to make sure that the runners work smoothly, not hanging up due to crud built up on the plates in the lower intake manifold, or a problem with the linkage.