86 s10 blazer, looses power at 45-50 mph

Maintenance/Repairs
1

I have an 86 s10 blazer. 2.8 v6. It starts and runs fine cold at low speed. At 45-50 mph it won’t go any faster and will stall when I stop. Will restart in 5-10 minutes, but runs ruff. Here’s the kicker. When stopping after trouble starts, braking becomes very hard, obviously loosing vacuum. Replaced 02 sensor and control module and all standard tune up parts.

2

Restricted exhaust is a likely cause.