bought this 1994 3.0 V-6, 4X4 in 2007. 137 K miles 2009-Passed smog. 2011 smog comes due again. 148K miles. Passed all phases except "gross polluter" at idle, which was missing a bit. Investigation led to computer and connection according to my smog/auto electric guy. Where computer emerges from firewall...pull toward, idle smooths out...push toward engine, nearly stalls. Removed computer and took off cover to look for loose connections, burned components, or circuit board problems. Nothing. Mechanic was scoping engine and after reinstall...discovered that computer now was not sending signals to engine. Kept the car for three months...no charge to me...was just about to give up when he decided to check the distributor. Removed new cap and wires to find the distributor bearing was worn and rotor was dancing or deflecting off distributor cap. Replaced distributor and another new cap and rotor...idle fixed and now truck was ready to pass CA smog-almost. computer was still not sending signal to engine...cause unknown...but we decided to test and yes it passed smog. So I'm driving it, but always wondering because power falls off at higher speed say 85 mph, but drastically on grades. It seems like it had more power previously, but can't be sure. Truck has 5 speed. 4-6 % grades require 3rd gear sometimes. Feeling is that spark is not advancing as RPM increases. Mileage seems OK. truck has 5 digit odometor so 48K showing could be 148K or 248K. Engine is tight, clean, no leaks, good compression. Can it really run this good without a computer signal, pass smog, and run out of steam prematurely on the highway for loss of the computer signal? Top speed is just about 85+ MPh. Tires are 30X9.5 15LT Goodyear Wranglers 45 PSI on alloy rims with 1-1/2 " offset greater than stock 70 MPH true (garmin) comes at about 2650 RPM with current tires and wheels.