WOW, lots of info, thanks guys. OK let me try to answer all the questions.
No coolant leak and its not low.
Distributor, not sure where it came from, the original one broke (shattered its guts in the driveway one day) and I picked this one up (new) from my mechanic neighbor. It was changed about 3yrs ago, but I do remember that the trigger system inside it looked different. They told me its a design change because the older ones shatter like mine did. It plugged right in and ran fine after that.
Thermostat is a 190 (I believe) its been in there for many years, no signs of anything strange on the temp gauge.
Timing is correct, they check that now during the smog check. And it passed.
Not sure how the injectors are firing, but they are noisy.
Also not sure of fuel pressure, there is no place to check it on this truck. If I remember right its a low pressure system, its supposed to be something like 12lbs I think.
I replaced the base gasket for the TBI a few years ago too, forgot to list that, sorry. It had the high idle issue and ran like crap.
Not sure how rich it is, it did pass its smog test (barley), but both the smog tech and the mechanic looked at the test sheet and said its rich. I think the only reason it passed was because it has 2 brand new cats under it. The old cats, front one was hollow, gutted its self and plugged the rear one. Exhaust guy said running rich can cause that, burning fuel in the cat (??).
There is a slight exhaust leak on the pass side manifold, goes away once it warms up. but the 02 is on the driver side (I think).
It has 116 k miles on it.
TPS sensor was checked and is in spec.
I think I did see the 02 sensor switching with the scanner (looking over a shoulder), nothing occasional or random about it, looked like square wave signal.
There are no trouble codes, and it never turns on the check engine light no matter how bad it runs.
Heres a little description of how it runs and what it does.
Truck cold, hasnt been driven in a few days, get in start it and drive away, after a few blocks it will develop a slight stumbley miss at cruise speed, this goes away at full throttle. If I shut it off (once its fully warmed up) go into a store to get something come back out and drive home the truck runs better, not perfect, but better. If you dont shut it off, lets say you just jump on the freeway and drive, it runs like crap. It misses and has no power, sounds and feels like a lack of fuel (plugged fuel filter). But as soon as you hit full throttle it clears right out and runs good (no missing). Back to cruise and it starts all over again.
This is worse in the winter, not as bad in the summer.
