This morning on my drive into work I discovered that when trying to accelerate while moving at ~60mph or more the car would shudder and experience a lack of any power at all. If I continued to press down on the accelerator the car would continue to shudder and it would get worse. It felt like an engine stall shudder but constant. If I was below 60mph are tried to accelerate I had no problem, I could continue to accelerate all the way to 70mph, then I would have to slow down for traffic. However after cruising above 60mph and then pressing down on the accelerator I would experience the shuddering. I experienced this issue suddenly with no gradually increasing issues at all.
1993 Ford Escort Wagon LX 1.9L SEFI
Recently replaced oil, about 2wks ago
Air Filter fine and unobstructed
Car has been getting about 36mpg
Exhaust was replaced about 1 month ago and is unobstructed