2000 nissan frontier after it warms up few miles it starts spuddering real bad like is barely running peddle to the floor not so much when weather is cold outside temp seems to make a difference

SOURCE: Car starts hard and runs rough in cold weather, undrivable

The correct spark plugs are very important. Glad to hear you got it fixed good.

SOURCE: The 2000 mountianeer starts and runs fine but shuts off

CHECK THE COLD START ENRICHMENT VALVE AND OR THE IDLE CONTROL VALVE. I AM ASSUMING THAT YOUR VEHICLE IS FUEL INJECTED. ONE OF THOSE HAVE GONE BAD.

SOURCE: from cold start engine warms to quater temp then

Does the Check Engine light come ON when this happens? Whenever the "Check Engine" light comes on, there is always a DTC (Diagnostic Trouble Code) stored in the ECM (Engine Control Module). You'll need an OBDII (On-Board-Diagnostics) scanner to retrieve any codes recorded/set in ECM. Otherwise, guesswork. I have MANY ideas that could send you on a wild goose chase. I strongly suspect EMS (Engine Management System) sensor beginning to malfunction as it warms up. First strong suspicion is the crank position sensor (CKP) - however,usually always sets a DTC (i.e., P0335, P0336). The next suspicion is the Engine Coolant Temperature sensor. The ECM uses this sensor's signal to adjust fuel, timing, engine RPM, etc based on engine temp. If malfunctioning at a particuar point during engine warm up, it could be telling the ECM the temperature is LOWER or HIGHER than it ACTUALLY is, resulting in the ECM to increase fuel (flood it) or give it LESS fuel (starve it). If this malfunction lasts long enough, the ECM will usually set a DTC for that sensor circuit, either a Range/Performance code, or a "LOW Input" or "HIGH Input" code.

SOURCE: Engine will not idle and run when starting in cold weather

Have a mechanic take a look at your throttle position sensor and engine idle sensor. Make him manually adjust them as opposed to just putting in new ones. It may require that you have to have a higher idle than normal. Your underlying cause is going to be that I am sure you have a lot of miles on your engine.

SOURCE: F250 Diesel engine won't start in cold weather

check your glow plug relay! located on the right side head