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"
http://www.auto-forums.net/ftopic2349.html ), I squirted carb cleaner
and found the leak appears to be where the butterfly pivot rod exits
the throttle body on the right (passenger) side, as the idle drops
drastically 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
Thanks in advance,