[aigel]

Check engine light is blinking?

That's code for a misfire.

How many miles on the truck? Sound like mine when the head gasket let go. There was a cooling system to chamber breach going both ways. A well warmed up truck would leak enough water that under load, the mixture was too rich to fire.

Do you usual checks for a head gasket:
- Exhaust in coolant?
- Pressure in cooling system?
- Coolant out of exhaust pipe?
- Coolant in oil? (Send the oil for analysis)
- Oil in coolant?
- Compression check
...

Good Luck!

G