Just wondering if any of you would know of a way to determine if coolant is properly flowing after the Tstat kicks in. I had the same bogging problems today after a longer trip on highway (most daily driving is in the city so it never gets hot enough) I've determined its either cooling, or an ignition problem, or a combination of the two. Currently I'm a little tight on money (and do for an oil change) and cant just throw new parts at it again, especially seeing as i can still drive the short distances around the city no problem. Regardless if I could I'd probably just replace the water pump, the radiator (needs to be done soon anyway) the cam, the timing chain, distributor, and maybe the computer (cuz i'm paranoid like that). Anyway my thought is coolant isn't flowing, so its not overheating like a car normally would because it the coolant doesn't get hot enough. I guess I can't rule out the fan clutch either, and should probably check the timing chain and distributor alignment... It's just thats a lot of work and money for investigating.

 

When the truck is cool, take off the radiator cap, start the truck and let it get up to temp and watch the coolant. It will be obvious when it starts flowing. And yes, it is safe to run the truck with no cap on, it just wont build pressure like it does with the cap on.