I haven't posted here too much yet, but have found some great advice so far and really appreciate it! Here's a question:
The Mikuni carb on my '88 2.0 Ram-50 has caused me nothing but trouble. The truck doesn't have much power until A) it's warmed up a lot, or B) you really gun it on the highway. It was worse before I discovered the secondary wasn't opening AT ALL; rerouting the secondary's line to a port with more vacuum seemed to help a good deal (there are lots of capped-off vacuum ports on this carb). I replaced the fuel filter and catalytic converter too--the converter especially was a big help. I also replaced the bowl vent diaphragm some months ago (which was visibly damaged), but that didn't do much good. I get about 23 mpg hwy, so figure everything's somewhat OK.
I don't know too much about the parts of a carburetor, but here goes: the primary and secondary each have a butterfly valve way down in the bowl, and the primary also has a choke plate way up at the top. The other day, I noticed that this choke plate is wide open all the time, even at idle. It seems to me that it should be almost closed at idle, and then open more and more as the truck accelerates, right? This would explain why it sounds fine at high speeds, but idles roughly (sort of a "wheeze") at stoplights and such.
Does this sound like something that's easily remedied? I know the throttle linkage attaches to and locks/unlocks this choke plate, since I was doing so with my hand (and then the plate would move freely--though still not close on its own). Maybe there's a problem with this linkage?