Topic: '87 22R (carb) rough idle

[gmrwizard]

My wife’s '87 pickup with a 22R Carbed engine started doing this about 6 months ago.
It would start up cold just fine, warm up and kick down off high idle just like it is supposed to most of the time. Every so often the high idle would be a little rough, then when it kicked down it would die.
It has been progressively getting worse to the point now it does this almost every time. If I can keep it running till it warms up it runs fine after that. One other symptom is #3 and 4 cyl not firing right, spark plugs show dry soot build up.

Done so far:
Compression test, 160 lbs. all 4 holes.
New plugs, wires, cap, Rotor.
New Coil, Fuel filter, Air filter.
Checked all vacuum lines.
No apparent manifold leaks.
Checked valve adj. Right on the money from last adjustment.
FSM EGR tests good. Tap test for sticking good also.

Got me stumped so far. HELP

Thinking about replacing carb with an extra one I have but don't know where to compare numbers for compatibility.
Thought it might be the Igniter but that is a $500.00 SWAG.

[toynorcal]

It's a carbed 87 

Well, the only thing I saw missing in your list of done so far is checking the intake for leaks. If the carburator wasn't bolted down in the correct sequence it will warp and get progressivly worse like that.

Do you have any trouble re-starting it?

Get some carb cleaner and spray around the base while the motors running and listen for RPM changes. Then use the rest of the can in your carb to clean it up some.

[gmrwizard [OP]]

Didn't have enough (insert name) spay to do a good leak test till yesterday. Picked up two cans of (big guns) starting fluid and did the spray around test. Found a vac leak at the #3 intake runner gasket.
Up till 2100 last night taking it all apart. EXCEPT for the one stubborn bolt (everyone knows that one stubborn bolt all too well) had to be the one at the back of the head holding the water tube clamp. You know the one, wants to break off not break loose. Soaking it with PB blast over night. Getting ready for round two after breakfast.