Have 1986 chev s-10 pkup. 2.5l 4-cyl, fuel inj 5-speed manual. When I start with engine cold (surrounding temp, any weather or season) there's a solid, dead miss. The further I drive the miss starts to gradually go away. Eventually about a mile, miss is gone. Doesn't return until engine is off, cools down. Never overheats, has gotten worse last several months, taking further to go away. Suggestions? Thanks. Ron

Consider replacing the Engine Coolant Temperature (ECT) Sensor, which affects fuel injector pulse width. The ECT Sensor is a temperature dependent resistor (thermistor), whose resistance decreases as the engine coolant temperature increases. It provides a richer mixture when cold, leaner mixture when hot. They become corroded, due to not changing the coolant frequently enough, flood the engine, and waste a tremendous amount of fuel.

Due to the age of the truck, I would also replace the Ignition Control Module (ICM) and coil:

http://www.autozone.com/autozone/catalog/parts/partsShelf.jsp?categoryDisplayName=Electrical+%26+ Lighting&fromType=parts&fromString=search&parentId=cat10012&currentPage=1&filterByKeyWord=ignition&isSearchByPartNumber=false&navValue=15700029&categoryNValue=15799999&fromWhere=&itemId=prod10610&displayName=Control+Module+-+Ignition&searchText=ignition

I recommend doing this every 120,000 miles or 10 years, whichever comes first. ICMs are problematic components on your truck.