So, the truck's been especially sluggish of late and on my last long trip, the idle dropped to 500 rpm plus or minus 50, so I started looking into it. Did a compression test (forgot to open the throttle body...) with the following results. 150/152/145 psi for cylinders 1/3/5, but 90/10/30 psi for cylinders 2/4/6. Took it to the shop, and they said they did a leak down test and the air was whistling out the dipstick tube. Oil is still brown and coolant looks fine too, not puffing white smoke, but a strong smell of gasoline in the exhaust. How likely might this be a head gasket vs. 3 cylinders all going bad? Haven't ripped into it yet to pull the head, just thought I'd toss this out to see if it sounds familiar to anyone.

On the one hand, I wanna do the 5VZ swap. But the budget isn't quite where I want it to be to do it right with a fresh motor the way I'd like to. However, I only have 135k on this motor, and I just dropped $1600 into it at the shop to have the timing belt and water pump changed as well as having the valve clearances adjusted at 120k. Had the exhaust totally redone to eliminate the crossover right after that trip to the shop and yanked the EGR system. I'd like to think the old girl still has some life left in her without having to do a rebuild...

Thanks for the input!