I concur re: spark plugs--
Platinums should be given the flotation test.
Throw them in the river-- if they float, you can re-use them.
Seen more than a few horrible running mid-80s V-8s fixed by going back to
proper plugs.

My dislike of platinum plugs does not extend to cars designed to run them.
NOT trying to start a platinum plug debate--
if they work for you--peachy.

If the injectors are steel-- give them the flotation test as well.
Updated injectors are brass. Replace seals as well.

No EHA on an 85.

Fuel distributor or warm-up regulator are likely culprits.
Fuel pressure test will show bad regulator.
For Distributor. we fabricated a test rack with eight clear graduated cylinders and a set of fuel lines made of Tecalan fuel line and fittings.
Allows inspection of injector spray pattern, as well as differential volume readings per cylinder(injector) Test can be re-run after swapping injectors cyl to cyl to identify either bad injector or distributor.
Contact area shops-- find someone with the proper test equipment. You don't want to guess on a fuel distributor.
Bosch sells a fancy version tester, ours does the same thing.

Fuel distributors have gotten ungodly expensive from Bosch($1400-1800)
the last I checked. We have had fairly good success with an outfit called
Python fuel injection for rebuilt units.
Do not take a fuel distributor apart--
you are asking for trouble. I know of no source for internal parts or selas/o-rings..

__________________
Todd Haven
Parts Manager
MPH Automotive
Houston,TX