Car lagging when i accelerate?

[dobes]

Hey guys
I have a 1998 VT Exec, all was going sweet with it until I got it serviced a couple weeks ago at Holden and now ive been having some issues with it
First up, i was driving to work then the temp gauge started climbing. Checked the radiator cap and no water or nothing was spewing out, so i just topped off the coolant and then no dramas.
Couple days later when i was driving, as i accelerated it was sort of lagging and was just chugging along, like stop and start etc. The temp gauge started to climb slowly, and again the radiator cap was fine and i topped off the coolant and it was fine.
But today, it was lagging a lot, so much to the point that my car would just stall. Did the regular process, but the radiator cap was spewing with water, coolant was full, but the temp gauge remained the usual. Left the car for a good couple hours, now it works fine. But im quite scared that itll happen again
Im no mechanic, but just putting this out there that my spark plugs havent been changed in a while, year +. Timing belt hasnt been replaced either (car is at 192,000 k's) and im running on Duel LPG. My tank has about 5 litres petrol and 30 litres of gas if that helps?

Anyways
Much help would be gladly appreciated!

Thanks guy

[Brett_jjj]

These engines dont use a timing belt,do you mean the serpentine belt at the front of the engine?.Id be taking it to a radiator specialist or mecahnics and get them to do a pressure test on the cooling system,also get the engine compression tested at the same time.These tests will show up any leaking /blown gaskets in the cooling system/engine.The V6 has a bad habbit of blowing inlet manifold gaskets which causes all sorts of problems like bad running and overheating etc.

[Mick1988]

Sounds like it's a blown head or head gasket.

[showbags]

had the same with my vt. replaced the radiator and it hasn't done it since. dont ask me why, cause no one can tell me either.