Motor sounds funny after pressing brakes really hard?

Yes, With the vehicle off the brake is really hard when I press them it doesn't sink at all then. Yes, when I do start the vehicle the brake does sink a little. I just had a new brake master cylinder installed. But the brake booster is old.

Here is what my van did this time. I drove it home after getting the master brake cylinder replaced. Looked down and my CEL was on again. And I just did a scan and it says what it always says lol System to lean in bank 1 and system to lean in bank 2. I forgot to wrote the codes down but it did say that.

Sorry for having so many threads going. I forgot how you have to verify your question via email. But I just made a new tread regarding this so you can delete this one. If you have too etc

Sure I took a picture of my scanner. It did say lean bank 1 and 2 but it shows another code P1000. I've never seen that one before. And ok I will read over the guides. Also, this is how it behaves. When you step on the gas it sounds normal. When I put the van in park it sounds normal. But when I am driving along and I come to a red light or stop sign and press the brake is when it the motor sounds funny. Idle then slows down. Idle then slows down.

Ok =P1000 code / When I press the brake I can hear something that sounds like air escaping But I really can't tell the motor of the van is pretty loud. I am pretty sure it is but the motor is kinda loud etc But when I turn the motor off I can hear some air escaping sounds though 100% sure on that. I hope this fixes it. Because installing a brake booster cost alot here. I will let you know what happens. If I can I will try recording some audio so you can hear how it sounds. Etc

I hope that replacing the Brake Check Value is the problem. I've done the, Turn the vehicle on test while holding the brake and my pedal would sink alittle. And after turning the van off the brake pedal would get really hard and you could hardly move it. Etc I can't reach the check valve to pull it out to see if I can hear any air escaping. I will have to get help for that test. I have even done the bubbles showing up while pressing the brakes in the master cylinder fluid reservoir too. You can see it bubble too (sorry I forgot to tell you guys I did that test too). But yesterday my van stalled on me for the first time, since my fuel pump went out me some time ago etc. So I am going to quit driving it until I can at least get the brakes part fixed. I nearly ran into someone. That part was scary. Also, the last time I scanned it the error codes I seen where P0174 and P0171.

Well you asked me if I pull the check value out could I hear any air. And no, I didn't hear any air coming out of it at all. I had someone to pull it for my today while I was around and I didn't hear anything.

Ok. Thank you for letting me know. :-) I just bought a brake booster today too. The weird thing that gets me is when you press the brake and then start the van the brake pedal sinks just a little and that's it. Alot of people on many other websites says there is nothing wrong with your brake booster lol But yet when you press the brake in normal operation the vehicle acts like its going to stall. Like mine does. That's not normal.

Ok I will let you know what happens. And ok I will look at the guide. Do you write the guides yourself? If so you have done a great job.

Ok Ken here is the update. The repair man just told me that my master cylinder is leaking in the brake booster and he said my van will need a new master brake cylinder. He also said that my van will need what is called a brake booster switch. I haven’t ever heard of that before in my life. And here lately I have been watching tons of brake related videos on youtube and NONE of them have ever brought that up. Then I asked him well, did you get the new brake booster installed. He said no because my master brake cylinder was leaking. And I sworn I heard him say that he sent back the brake booster. Which is impossible I bought that and I have the receipt. So maybe he meant he sent back the new brake master cylinder they bought. Then he asked me have I ever seen any leaks on my drive way and I told him I haven’t seen any until I back out of my drive way. Anyway, what was going to cost me $240.00 is now going to cost me $300.00. At least that’s what he told me. Well that is the lastest. I know its not much to go on but that’s what I was told.

Ok I will let you know. But does a 2000 Ford E150 4.2L V6 Econ van even have a brake booster switch?

Update: Ok I have brakes the kinda sink a little bit but my motor no long stall or idles rough when I hit the brakes. Picture to the left is the old one. And the pic to the right is the new one etc.

Yes they work but the ABS light is still on. I don't really care if the ABS light stays on or not now. I am just glad I have brakes etc. And my check engine light is still on too. But I will make a new thread for that one. Once I Scan my van again. And you for the images. And thank you for helping my with my brake problems yet again. You and others as well.