This is a bizaar situation. Whenever I released the brakes even when driving at a normal speed engine dies as if someone just flicked a switch. When I quickly press the brakes engine picks back up and runs. I’ve tried this is reverse as well. It has an automatic transmission. Engine runs rough at idle as well. Anyone ever encounter this?
Try a new check valve for your brake booster.
When you DEPRESS the brakes, the engine runs BETTER. I caught that.
It’s usually opposite. The engine may be running too rich. When you depress the brake, the brake booster allows air to enter the engine intake, which makes the fuel / air mixture less rich, and the engine likes that mixture better.
Well, you need to fix the brake power booster.
The engine is running too rich. Several things can cause that: dirty air filter; fuel pressure regulator not reducing fuel pressure; engine coolant temperature sensor (ects) bad; reduced air flow through the dirty throttle body throat; dirty sensing element in the MAF (Mass Air Flow) sensor.
Get your repair manual and check those sensors with a multimeter. Use a throttle body cleaner to clean the IACV and throttle bore and throttle plate. Use an MAF cleaner, change dirty air filter, and do the other tests / checks in the repair manual.