Car sputters when I floor the gas

[ezlnh8u]

Hello fellow r3vers, I have a 1976 2002 with a m20 swap from a 91 e30, the car has been running fine for the past year, until about 2 weeks ago my rpms idled at 3k on neutral, switched the maf and the rpms went back to normal.
But now the car slightly back fires and it sputters when I step on the gas to the floor, I checked for vac leaks and found nothing, not sure what else should I look at? Many thanks in advance.

[blizake500]

I have the same problem. Only when cold though. As soon as it warms up its fine.

[Vincent Brick]

I'm going through some similar stuff right now. You said MAF but I assume you mean AFM, what did you put in there, was it used out of a junk yard or other car?

[ezlnh8u]

It was used, from a working car.

[theKrampus]

Check your plugs/wires for cracks. Was it on a humid day?

Mine used to do that, but it ended up being moisture in my distributor cap. I wd-40'd it and tightened it down good. Never had a problem again

[ezlnh8u]

I will try that, thank you, I will update in the results.

[ezlnh8u]

So I replaced all the plugs, checked cables for crack, and still have some backfire, I unplugged the maff, and the csr ran without any back fire, does this mean that it could be the maff?

[Jica06]

Check/replace front O2 sensors. Fuel filter? Make sure air box is fully connected.

[lambo]

Mine used to do that, but it ended up being moisture in my distributor cap. I wd-40'd it and tightened it down good. Never had a problem again

Interesting. I'll have to check that on mine.

[ezlnh8u]

I have aftermarket air filter and checked to make sure the clamps are tighten enough, so should I rule out the maf then?

[ebox86]

exhaust leak? have you checked the manifold/headers for leaks/smell?

[Liquidity]

Way too many possibilities for what could be wrong. And what exactly was your process for checking for vacuum leaks?

[ezlnh8u]

There is smell,what I noticed is exhaust fumes in the cab.

[ezlnh8u]

Vac leaks, we used a smoke test.

[theKrampus]

Fumes in the cab could mean a shot cat... Or a leak at the headers possibly. Could be dumping too much fuel, and that's why also. Check to see if an injector is stuck open? Then you'd be flooding one cylinder. Would cause issues for sure