Blinking Check Engine when accelerating through 75

[andr3w]

Sorry to crosspost, but I really could do with an answer.

I drive a '96 ford aspire, manual trans. Sometimes (Not always) while on the freeway, when accelerating through 75mph, the check engine light starts blinking. So far every time this has happened I've slowed down to 65 or slower right away, and then it stops, and the light just remains solid.

I want to think my sparkplugs just need to be replaced, and it's misfiring a little because they can't keep up with the engine at this speed-- the car has 60,000 miles and they've never been replaced. When I got the clutch replaced, the mechanic said they could do with replacement "soonish"

After a little while of the Check Engine light being solid on, it goes out on its own, so I've not worried about it that much.

And I've checked the engine. It's in there.

It does, however, scare the crap out of me, can anyone offer any wisdom?