I'll hit quote on your post but I seen I think shiftpro mention WeeOFives should have never been put in these trucks. I agree and GM probably does too. Being a smog tech in Cali back in the late 80's into early 90's I know a little about that. The code you mention was the LE9. The most common truck engine of the 80's in the GM light duty pick up fleet. 305 cubes with ESC (Electronic Spark Control), and in Cali emissions trucks they had CCC (Computer Command Control) system with feedback E carbs for AF mixture and such.
This is also when trucks started getting more of the taller gears like the 2.73 and 3.08, station wagon gears and the attempt at coming up with an OD transmission that was a flop riddled with problems. This was all done due to meet the EPA standards of avg mpg for the manufactures fleet, and reduced smog emissions. This is when Cat Converters were added to vehicles, Lead was taken out of fuel, and the manufactures to get there way underpowered engines by reducing compression, adding NOx (Nitrogen of Oxides) bumps in heads that are restrictive adding AIR (Air Injection Reactor) better know as smog PUMP, when it actually INJECTS air right at the exaust valve just as exhaust exits the head to create a reburn of the exhaust gasses. Without getting more technical, the EPA and US standards is why in the late 70 and into the 90s is why vehicles are so gutless. Technology is catching up finally and we've been getting our horsepower back over the last several years.
We bitch about our emissions and mpg requirements, Japan's have been way way worse for many many years. Anyone ever heard of these used engines for imports that have usually 40-50,000 miles on them and we can buy them here in USA? It's true. You can buy Honda, Toyota, Nissan and such engines used with 40-50,000 miles on them for about 1/3 the cost of a new engine. Alot of it has to do with meeting emission requirements in Japan. After so many miles, like a well broke in engine over there, it's getting a little carbon on the pistons, uses some oil, as in maybe a quart every 5000-8000 miles etc, it won't pass their emissions so usually it's cheaper to buy a new car than try to get it to pass emissions. Lots of good cars get **** canned in Japan.