Engine Missing, I'm out of Ideas

Hello,

I love this forum, I have read through the posts and used it as a guide in attempting to fix this engine miss.

My engine misses constantly. It runs, but it has a miss that I cannot seem to fix. When I floor it, it runs smoother.

I occassionaly see white smoke coming out of the tailpape.

Originally it was throwing Code 33 and 45 with the check engine light on.

Now it is only throwing code 45 after the following:

1. New spark plugs, wires, cap and roter
2. New MAP Sensor
3. New TPS Sensor
4. New Oxygen Sensor
5. AdjustedTiming
6. Cleaned EGR (hardly any carbon)
7. Replaced Fuel Pressure Regulator
8. Checked Vacume Hoses
9. Replaced Fuel Filter
10. Replaced Fuel Relay

I cannot think of anything else.

If anyone has any suggestions at all, I would appreciate it.

1992 S10 Blazer 4.3 V6 TBI VIN Z

Question about the white smoke what does it smell like? Are you sure it is smoke and not steam. What are the running conditions when this happens. Engine cold or hot, does the temp outside affect it. 

It happens when the vehicle has sat for awhile. Usually an hour or so. Also, I am sure that it is not steam, it is defenitely smoke, it smells like fuel. Also, it doesn't seem to matter if the engine is hot or cold. However, I have observed it to be more frequent when the engine is cold.

Have you checked your coolant level? It sounds like it might be antifreeze burning. Do you notice the smoke when you accelerate from a stop, just on engine start-up, or while cruising?

My coolant level is fine right now. I just replaced the radiator last week. I have had this problem since before the radiator was replaced, however, my old radiator did seem to use some coolant. I'm new to auto mechanics, but how could a coolant leak cause white smoke and an engine miss? (Like I said, I'm new to all of this)

Thanks!

One of the possible outcomes of a blown head gasket would be burning coolant. It allows coolant to get into the cylinders where everything burns so it evaporates with the rest of it and makes a white cloud come out of the exhaust.
 
Basic rule of thumb white smoke is coolant, black smoke is oil.

You can definitely diagnose a blown headgasket with a compression check.  Compression gauges aren't prohibitively expensive ($20-$30) and will tell you quite a bit.  If you find a cylinder that is low, squirt some motor oil into the cylinder (through the sparkplug hole) and spin it over for a bit.  Then recheck the compression.  If it comes back up, then you may have a problem with the rings in that cylinder, if it doesn't, then it is either a bad valve or a blown headgasket. 
 
You can also read the spark plugs or get a combustion byproducts tester for the coolant.  Good luck!

Definately sounds like a head gasket as Kyle said take a couple of the plugs out and visually inspect you can find the pictures of plugs in the back of one of the manuals that you can get at Auto Zone or I think O'Rielly's it can tell you alot about whats going on but I definitely think it is head gasket or some type of leak along with a bad valve or valve seal like Kyle said. Thats why I asked you about the smoke and smell, sometimes not alway it kinda smells like a gas / kind of anti-freeze mixture smell. 

A bad coolant temperature sensor will also cause this kind of problem. Just google how to check the coolant temp sensor. Or buy one for 15-20 bucks to see if that is it.