How can i check the emc to see if it need to replace or not

Your guessing ,have no clue ! Replacing parts instead of testing electical circuits an doing a diagnostic scan of all the control modules rarely work's . changed starter,fuel pump,emc and relays are good and had a new key re coded. It still will not crank. Your best bet ,take it to a qualified repair shop.

Is it a code reader or a scan tool ,there is a difference ! An some will just read OBD codes from engine control module . You need to take it to someone who's scan tool can check all modules on the vehicle . Then again in some situations the factory scan tool will only work ! Everything You Need to Know About Scan Tools with John Anello

I suggest putting a pressure gauge on the fuel line bleeder valve and check the pressure coming from the pump. If the pump is getting weak it will cause the truck to surge. Could also be the catalytic converter stopping up as well. I'd check fuel pressure first. Hope this helps you out.

you are gonna have to take it to toyota and have it flashed to your vin #

Have you tried o add block heater? Robert Calgary, AB

This code is a generic powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996-newer), although specific repair steps may vary depending on the model. The Powertrain Control Module (PCM) / Engine Management Computer (EMC) / Engine Control Module (ECM) has detected a fault with the circuit that controls the vent for evaporative emission systems vapor. As fuel sits in the tank it lets out fuel vapor, while driving this vent opens and allows the vapors to be circulated into the engine intake manifold, a charcoal canister or into the atmosphere, depending on the vehicle. This vent valve is apart of the simple, yet complicated evaporative emissions system. Symptoms Symptoms of a P0449 DTC will include Malfunction Indicator Lamp (MIL) illumination, you will likely not notice any other symptoms. Causes Potential causes may include: Faulty vent valve Wire/circuit issue PCM/EMC/ECM fault Possible Solutions Some steps to take to diagnose and repair this trouble code include the following: Check your fuses, there may be a fuse that powers the vent solenoid. Check for a rubbed-through or chafed wiring harness. Check both wires to see if they are shorted to each other, to ground or power. Visually inspect the vent valve for cracks or damage. Trace the wires to and from the PCM/EMC/ECM and check for continuity continuity using a digital volt ohm meter (DVOM). If you have access to an advanced level scan tool, actuate the valve while reading power and ground at the connector or by simply using a bulb wired to both terminals, it will light up if power and ground are OK. Using a DVOM, check the resistance of the vent, in most cases the resistance reading should be low, refer to the manufacturer's specification or compare it to a new one. Too high or low a value indicates a faulty coil inside the valve, thusly meaning replacement is necessary. This code seems to be prevalent on Dodge, Chrsyler, and Jeep products. In those cases the vent valve was bad. With GM products (specifically pickups), GM has released a new updated valve assembly. Finally, remove the valve, you may be able to access the pintle inside and it simply could just be sticking from fuel residue. Clean it and retest.

Read more at: http://www.obd-codes.com/p0449
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code 1729 is EMC SHORT TO GROUND. YOUR EMC TCCU CONNECTOR LOSSE OR POOR TERMINAL TO WIRE CONNECTOR.POSSIBLE RAIN WATER CAUSING SHORTING PROBLEMS,WATER AND ELECTRICITY DONT MIX.

it sounds like an intake vacuum leak to me. check with propane or acetylene

You could have a dirty fuel filter and needs to be replaced, Best thing to do is to retrieve the DTC codes from the ECM to find out why it stalled. 
You can go to Auto Zone where thay can scan your EMC for free and clear any codes, If there is no Auto Zone close to you and you are willing to retrieve the codes your self, here is a link on the instructions to retrieving the codes and clearing them.
http://www.allpar.com/fix/codes.html

Good luck and keep me posted, be glad to help you out.

The Service Light indicates that the EMC has detected and problem and needs to be addressed. Your going to have the get the Blazer scanned for DTC codes which could be a simple problem as to a faulty Gas Cap to a bad O2 sensor. 
Sorry can not help you more then this but most large auto parts store like Auto Zone will scan your blazer for free and some auto shop charge as low as $10.00 to scan and reset the ECM.
Good luck and hope it's something simple.