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 guess.

 

Sounds like the ECU is getting a false signal, maybe "thinking" its warmed up when it is not. Not a very profound observation I suppose.

I suppose the good news is that nothing "expensive" is bad, if you don't count your time as money.

It does sound like the automatic choke is not staying engaged, much like if you shut off a manual choke too soon, right?

If so, what does that manual choke do, he asked rhetorically. It shuts down the air a bit, and provides a little extra gas. Does not sound like gas is the problem, as when you provide it manually, you still have a hard time keeping it alive, right?

So that leads me to air. Could the AFM be being told to open up the air-gate too early? Maybe it is malfunctioning, or the temperature input to ECU is not right.

Just thinking out-loud....

 

Try spraying some WD-40 around the intake gasket and Carb. base and listen for a change in RPM. Could be suckin air at one of these points due to a bad gasket or loose bolts, it does happen.

 

Didn't have enough (insert name) spay to test this 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.

 

I would not think drawing extra air in one intake would explain your symptoms. Drawing extra air in, is the right direction, meaning cutting off air during warm-up via the AFM (as in a manual choke) is being circumvented to whatever extent, on that cyclinder, during warmup. After all, losing one cylinder won't kill the engine if all else is right.

I am assuming the leaking intake is uniquie to that cylinder, rather than a common plenum. If it is an area common to all cyclinders, then, yes, that could explain the problem. When totally warm the engine can handle the extra air, and in fact the leak may be reduced a bit with the expanding metal.

In any event, good luck this morning.

 

Your right. Irregardless the leak had to be fixed.
But the new manifold gasket didn’t cure "the" problem. Replaced the AAP diaphragm while I was in there. Old one looked ok. I’ve about run out of ideas. I think I will go ahead and change the EGR Valve. It was acting a little funny while I was testing it. Don’t know where else to look.

 

Please, for the love of god, don't replace the carb before you try this:

Check the vacuum advance on the distributor to make sure it is working. It's very common on at this age for the advance to go bad. I know when it happened on mine, it would no longer fast idle, and I can see how in combination with a vacuum leak it could kill the engine before it is warmed up.

It's supposed to work by advancing the timing to 12° at idle. Easiest way to check is with a vacuum pump, but you can also disconnect and plug the vacuum line at idle when the truck is warmed up, and the idle should drop... the engine might even die. If it does, then the advance is ok. If there is no change, then replace that sucker and I bet it will solve your problems. PN# 1922035140, about 95 bucks from http://www.1sttoyotaparts.com/


When I had this problem, I made the mistake of replacing the carburetor with a 'profesionally rebuilt' model and I've had to tinker with it on a nearly weekly basis ever since. I probably could have gotten away with just replacing the advance if I had diagnosed it properly in the first place.

 

dont replace the carburator huge mistake! i did and what a mistake i've had to mess with it for the first 2 years to get my 22r to run right. it was my vaccum advance just like noted!!!!!!

 

wow... thread resurrection again.