Quadrajet choke not opening

[83GMCK2500]

Back to the forums, need some help. Past couple days my truck has been failing to come down from high idle. Cold, hop in, set choke (depress accelerator), fires right up. Let it run while I scrape windows and drive off. After several minutes of driving it is still on high idle, now that it is warm it's even higher. My high idle screw is set to about 1,200 cold, after warm it runs between 1,500-1,800. I can pop the hood, lift air cleaner, and flick the choke linkage open and it stays open until I move the accelerator. Moving the accelerator triggers the choke linkage and it closes again and raises the idle.

Carb rebuilt a year ago, all linkage is clean and moves freely...but something is sticking somewhere.


Side note: seriously getting tired of working on my truck lately. We haven't had any "what did you get done..." threads lately but:

• fuel pump and new battery (all connections cleaned and sealed)
• timing set and all new front seals/gaskets + oil pan gasket
• oil pan gasket, yeah I know I just listed it...I hate it so very much. Laying out in a parking lot in the evening with barely enough clearance to get the pan between the front axle and the engine. Trying to line up that floppy blue f---ing felpro bastard and get bolts started. Rapidly decreasing light, exponentially increasing anger...
• re-timed after pulling distributor and going through it.

*Disclaimer, I don't find any of what I have had to do to be a particularly difficult task until you add in the fact I am in college taking 5 classes (20 credits, overload from fulltime), I am laying out in the apt parking lot with no jack or jackstands, I have been chasing a "poor running condition" (time consuming), and spread this out over a couple weeks during which I have midterms. King-sized frustration. FWIW, the poor running condition was a timing chain with about 1.25" of side-to-side play. Truck barely drove down the road at 50mph, stumbling. I pulled cap & rotor, cleaned contacts, new plugs, several other little things before I pulled the timing cover and discovered a nearly jumped set. All back together, timed, and it's been running GREAT for 2 weeks. Bonus: fuel pump did die and first cold snap did knock out my 9 y/o battery. Now carb is being a *****...