I have a 09 1500 4.7 ,hard to start, will not stay running multiple misfire showing on scanner, I have replaced new throttle body,all new coils,new map sensor,air temp sensor,new crank sensor.plugs are not that bad.and I don't know what to do, please help
I have good fuel pressure and good vacuum pressure

 

Which cylinders are misfiring? Have you done a compression test, or leakdown test?

 

It just shows code p0300, compression is good leak down is in with range, that's what's weird in the Drive-Thru waiting when I go to place my order I shut the truck off for about 5 or 10 minutes go to start it back up and everything went to crap.

 

Any other codes?

Some folks have had a bit of success with running another ground wire for the throttle body..... Aside from that, if you have a scanner that can read live data, see what the various sensors are saying, see if there are any pending codes.

 

No other codes, I do know you have to to put the gas pedal to the floor to start it

 

Hhhmmm... Generally, putting the pedal on the floor puts the PCM into "Clear flood" mod, and it dials back dramatically on how much gas it gives the engine. Usual culprit for that is the engine coolant temp sensor.... (or the wiring for it) Do you have a scanner that can read live data?? See what the PCM thinks engine temp is, when it is stone cold.

 

Just replaced the engine coolant temperature sensor and it's still doing the same thing ugh I do not have a scanner to do live feed on it

 

Think yer gonna need one to sort this out. Otherwise, it's going to be throw parts at it till it works right.....

 

The truck won't stay running long enough to try to do a live feed on it

 

Will it stay running if you keep your foot on the gas?