Pressure out the oil cap,runs rough,barely passed emmisions,gets hot as hell,check eng. light on,stalls out. No steam out the tailpipe. people tell me its a pcv valve and not a head gasket. If so can you send a diagram of where the pcv is.

The whitish gunky stuff is mayonnaise - an emulsion of oil and water and yes while it is considered to be a sign of a failing head gasket, it is often normal with some engines operating in cool damp conditions, especially when maintenance intervals are long and the engine oil is not among the best quality.

The presence of mayo can be considered no more than a clue to be stored away and used if other classic head gasket symptoms are displayed - excess amounts of cold start steam and water droplets from the tailpipe, a misfire on cold start that disappears fairly quickly, residual pressure in the cooling system of a cold engine and a steady coolant loss with no external leaks.
Generally three or more symptoms are needed, though residual pressure is a real indicator...

As the engine light is on a code read will be needed to begin the diagnostic process.

Check oil and coolant levels (at the radiator cap) first. Run fault codes to find which sensor triggered the engine light . The light is to tell you that the engine is in danger of failure so do not dismiss the light as not important.. Hot smells mean that the engine is very hot and you may not have any coolant in the system to activate the temp light or gauge.

Likely the heater isn't blowing hot because the coolant level is low. You need to look at everything...hoses, under the pump pulley, radiator, both sides of the engine from underneath and check the tailpipe for steam. No one can tell you what's leaking without looking at it. There are too many items that can leak. Look carefully and you will find the problem. When checking, look first with the engine cold and the cap removed. If you find nothing, put the cap back on and run it to build pressure and look again. (careful working near fan and belt...you can get hurt there)

first have the cooling system and cap pressure checked, system should hold pressure forever, and so should the cap, running without thermostat will cause uneven engine heat and affect emissions

No it will not, you need to have the knocking sound checked out, it could be rod bearing, or timing chain tensioner, both will damage engine, also need to check fuel pressure and ignition coil packs.

So..... you replaced the pump because it stalls, or it ran ok, and you replaced the pump and now it stalls? Stalls going 50 mph? idle? hot? cold? ck eng light on? codes? Fuel pressure?

TO SAVE YOU TIME AND MONEY.HAVE TRUCK SCANNED TO SEE WHAT CAUSES SERVICE LIGHT TO COME ON.YOU CAN GO TO AUTO ZONE THEY WILL SCAN IT FOR FREE.BUT IT SOUND LIKE YOUR O2 SENSORS COULD BE BAD.

If thermostat is new and you correctly filled radiator by filling while running and let level drop so all fluid goes into block and then fill up radiator again, then you either have faulty temp sensor or plugged exhaust.

You got it... most likely the head gasket...

Other symptoms:
1. White smoke out the tailpipe and excessive water dripping out of it.
2. With radiator cap OFF and car running, there will be frequent bursts of steam and water (careful! it may be violent).
3. Oil dipstick will have a "milky" goo ... that's water mixed with oil.
4. Overheating can be alleviated in an emergency by running with a "loosened" radiator cap.

Check cylinder compression to confirm that two adjacent cylinders have low, and nearly the same pressure. That confirms blown head gasket.

Hope this helps!

The plug is located at the bottom of the steering column.The fault seems to be the mass air meter though.