Idles good, dies when i put it in gear

you changed the spark wires but did you change the plugs..and if its a carburetor check the distributer as well

loose wire in ignition system.

Check all fuel lines for leaks, make sure it doesn't have bad gas in it. Listen for fuel pump when key is turned on. Change fuel filter. See if that's helps.

I’m happy to assist further over the phone at https://www.6ya.com/expert/kim_3202917d7c587455

is it fuel injected or carberated ?

It sounds like you might have a clogged catalatic converter on the exhaust system.

Fuel filter is either there or along the frame rail under the truck.You may also need to change the plugs,wires and oil.

did the same to mine I have an 86 same model as yours it sat for 5 years it would idle fine and run for hours in nutral then i put in gear and it would shake and eventualy turn off! took me two weeks to find the problem on mines it was a bad ctalitic converter and a bad distributor rotor it was not suppling enough spark to the plugs! now it runns like a champ talk about a real truck its a monster nothing close to it! all new trucks are junk they fall apart!

There is a control module on inner fender well under hood,natorious for causing this type problem,ussualy on drivers side.

We went to the website for Peak AntiFreeze and trying burping it for air. VOILA! Flushed and burped running beautiful now.

Are both injectors spraying gas? Make sure fuel filter wasn't installed backwards and remember if the fuel pressure drops below 9psi those trucks wont run. If injectors are sticking tap them lighty with a wrench and see if that helps