Started having the following problems, and the mechanic is stumped:

- Brake pedal is stiff...sometimes. Not a constant problem, but happens often. Brake pedal is very stiff or "catches" at the top. May take two or three attempts for the brakes to kick in. It may not happen for a day, and then happen six times the next day.

- When the cruise control is engaged, it will suddenly accelerate/decelerate in short bursts. Happens on flats, uphill and downhill. Eventually, the cruise control disengages. Again, this does not happen every time, but it does happen often.

- NO ABS light, engine light, or codes thrown. Whatever is causing the issue isn't causing an error code.

My regular guy couldn't find anything. Said it felt like the brake booster but he didn't think that was the problem because it was so random. I took it to another mechanic who said it looked like the right front wheel ABS sensor was malfunctioning. I had that replaced, but the problems continue.

Has anyone else experienced this or have any ideas? I'm about ready to scrap it because it's becoming dangerous.

 

it could be the vacuum. when the engine is switched off pump the brakes until the vacuum has gone put foot on brake and start engine the peddle should go down do this a few times as it seems to be random also get the vacuum pump checked out pressure/vacuum gauge
on the hose

 

Could this be a real brake booster check valve issue?