It sound's like the solonoid is getting heat soak, or in other word's, when it's hot it won't start, and as soon as the solonoid cool's off it will start. It will do this for a while, but eventually it won't start at all, this can be caused by several thing's, no heatshield on the starter, age itself will do it, if you can afford it, when you change the starter go with a 95 up starter, that's the first year of the smaller gear reduction starter. They not only have more power and start the engine faster, but because they are smaller they are less prone to heat soak, but they still need the heat shield that pop's on the solonoid. I have swapped many 88-94's to the 95 up starter. Also as a side note, you can use a starter from a 99-07 4.3 as well it's the exact same starter as 95 up obs use, but ls 4.8-6.0 etc. starter's will not fit, I have bought several from my local salvage yard from low mileage engine's, around here they go for about $30 Take it easy
