What does a coolant bubble feel like when driving?

[pgackerman]

Subject sums it up: What does a coolant bubble feel like when driving?

Can the driver tell there's a bubble anywhere other than the temp gauge?

[Raydar]

If it's a large bubble, you might be able to "feel" the coolant boiling in the pipes.
(I only say this because, at one time, I had a blown head gasket. When I was still trying to figure out what was going on, I could hit the gas fairly hard, and the compression would force the coolant out through the overflow. You could feel/hear the rumble when the coolant was blowing out.)

But, as you said, I usually would just notice the temperature gauge "twitch", with no other symptoms.

[GTRS Fiero]

Well, unless the engine overheats, nothing changes for the engine.  The water pump's effort to move coolant isn't enough to feel power changes as air pockets are encountered.

Yes, the temp gauge needle may move, or not.  That is a drastic thing.  Understand that the head into which the temp sensor is screwed does not change temperature that dramatically.  Normally, air pockets are not large enough to see a temp change.

You have the '7730 ECU, which will rapidly adjust to temp changes.  The ECU may change the AFR a bit.  You could possibly see this if you were monitoring the ALDL data.

If your coolant overheats, there will be an alarming sound coming from the overflow tank, as boiling coolant spews out.

[Fierofool]

I've experienced a bubble twice.  My 87 and Ray's 87.  Both times there was a loud bang that you could feel in the car.  The steam pocket came through the left side coolant pipe and hit the tank on the radiator.  On my car, it put a crack in the tank that required a radiator replacement. 

[pgackerman]

So whatever is bugging my car isn't a coolant bubble.  Here are the symptoms:

Driving back from Gray my car started chugging during acceleration.  Figured it might be a bad batch of gas.  We've been getting a lot of heavy rain and filled up (6.5 gallons) at a reputable -- but not my usual -- gas station before the drive.  This morning I went to COSTCO and put in 9 gallons of their best 93 octane.  The drive home was improved but not better.  Went for another drive this afternoon and the chugging has definitely not gone away.  Acceleration from a stop is also slower.  Has trouble maintaining 55 in 5th going up a slight hill with cruise on.  Slight smell of coolant, but don't seem to be using any, and the odor has been around for a few months.  No one else seems to detect it.

Work done this year:
Before July, new coolant reservoir from the Fiero store and all that implies. 
July, car wouldn't start.  New spark plugs, coolant temp sensor/ignition, spark plug wires.
August, new tires.
BTW, cat, distributor, and heater core replaced in 2014.

Any ideas?

[scottb]

EGR valve?

[pgackerman]

Possibility.

[scottb]

I dont know if you know the testing procedure, I think there is an article in the tech advice section. Not hard to do

[GTRS Fiero]

Coil?  Bad ground?