Here's what I've got: 92 S10 Blazer 4.3L "Z" M/T 4wd -Intermittent MIL -DTC45 Stored -Runs Rough at idle (often times it could be described as really rough--sometimes, not so bad) -Vehicle bucks while moving when engine is in "float" (between power and decel) at most any speed and intermittently under decel conditions--creating nasty manual-trans gear slap!! -Normal power -No Smoke of any color -No rich exhaust odor -Fuel Pressure = 12.75 psi with normal flow -MAP values normal (3 MAP sensors give same readings--bypassed original hose asm) Applied artificial vacuum to MAP with no discernable difference in performance. -New HO2S (O2 values do fluctuate, but not like they should--usually in the 750mv to 900mv range--very low, if any crosscounts especially at idle--usually zero at idle) Sensor was clean--not sooted from excessive fuel -TPS sweeps smooth (.78 @ idle) -CTS within 2-3 degrees of actual (Raytek laser thermometer) -Both Block Learn and Integrator are usually low (sometimes as low as 108--not always this low, varies a fair bit), but strangely Block Learn seems to change rapidly while the Integrator moves much slower. In this unit Block Learn is volatile so it resets when the key is cycled so no long term trends can be observed. -625 RPM idle speed -All grounds verified -18" vac at idle (steady needle) -Air Filter is clean -ThermAc unit in air cleaner housing pegged open -TBI unit re-sealed relatively recently--no seepage -No injector drip/leakage -Fuel pressure regulater replaced recently--no seepage -Pickup coil ohms out at 932 -Recent ignition coil -Recent cap, rotor, wires -New Delco CR43TS plugs--plugs looked even and normal, not sooted from excessive fuel -New muffler and tail pipe -Swapped TBI unit off another (identical) 4.3L "Z" M/T truck and experienced same symptoms--no change -O2 values go to 447mv when disconnected get good crosscounts also--Truck actually runs quite well with O2 disconnected. Still bucks when in "float" mode though. -CKT 453 is not open -Grounding CKT 412 drops O2 readings down to about 10mv -Canister is not fuel saturated -Oil changed to eliminate possibility of fuel contamination Problem started some time ago. Been checking things out when time prermits (and when the vehicle is stationary.....Wife's truck) Nothing seems to make a difference worth noting. This is starting to get a bit aggravating as I have dumped more time than I would care to remember into trying to figure out what is going on with it. At this point, I'm open to most any ideas.