I have a 1990 G20 van with a 5.7 engine, and it has a high idle, ~1500+ RPM. Following the recommendation of an earlier thread ("Help: 1988 5.7 TBI GM Engine - high idle"
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I squirted carb cleanerand found the leak appears to be where the butterfly pivot rod exitsthe throttle body on the right (passenger) side, as the idle dropsdrastically and becomes very lumpy when I squirt there. I found a wrecking yard engine that appears to have the same throttle body, but it also seems to have the same problem: the idle cap was removed, the idle screw backed all the way out, and I could feel noticeable up/down play in the butterfly rod, so I expect this is not uncommon. Apparently the bushing is worn, or more accurately the throttle body, since I can not see a bushing and I assume the rod wears on the aluminum of the throttle body itself.
The dealer wants $1296 for a new throttle body! That is about what the van is worth. Is there anything else I can do? Does anyone make a seal set or something similar? Is there a replaceable bushing that I did not see?
Thanks in advance, Parkerea