Sluggish acceleration and Popping sounds coming from Intake

[K43RU]

Hi guys, I have scoured as many forums and threads here and other Facebook pages etc. and for some reason I just cannot seem to find an answer to my problem.

Bit of backstory, I have a 1993 E36 320i Auto Sedan (with M50B20TU) and for the last year as the title suggests, have been trying to get this car back to how I first bought it.

The issue with this car is that it has a lower idle than normal (around 550-600), it hesitates when accelerating (almost like it plateaus meaning rev won't go higher than 2.5k or something near that), theres popping and banging (almost like misfiring) coming from what sounds like the intake manifold and on first starts & on take off it feels like its in limp mode and struggles to go past 1k rpm.

But K43RU, have you done x and y and z? Let me tell you, I have done (all new as well);

- Spark Plugs
- Coilpacks
- Cam Sensor
- Crank Sensor
- Fuel Filter
- Fuel Pressure Regulator
- TPS Sensor
- IACV
- Valve Cover
- Thermostat
- New Vacuum Lines
- O2 Sensor
- Intake Manifold and Gasket (Yes, I even replaced the manifold itself)
- Intake Elbow Boot
(Probably missing some other stuff, but you get the idea)

I've done the most I can with my little blue socket toolbox set. As far as my constant trips to the mechanics (yes plural) go, no codes really pop up. Some have said that there could be a vacuum leak from the Oil Filter Housing as both the gasket and small O-Ring need replacing (as its leaking Oil). Another has said that the timing could be off. And finally the most recent mechanic has said it could be a faulty Vanos. But you guys probably have some ideas before I spend another $2000+ to get these things sorted.

So, what I'm asking is, any ideas on how to solve these issues before I A) sell it and forget about it or B) Spend more money on it?

[Eric93se]

What is the fuel pressure? How old is the fuel pump? You've replaced vacuum lines but has the engine been smoke tested? You can buy one or build one both will be cheaper than a mechanic. Don't drive the car when its running so poorly, you might make it worse, backfires can crack the plastic intake. You need to do an engine compression test before putting more money into it. Your cat might be clogged, aftermarket cats are not as good as stock. Your speed sensor in the diff may be bad.

No, some oil leaking at the filter housing will not cause a vacuum leak. And no the vanos may need to be rebuilt but its not going to cause your main issues.

[K43RU]

I haven't checked the fuel pressure yet, but it still is the same original fuel pump from factory.

Haven't done the smoke test but did the test where you spray brake cleaner/ soapy water on the possible vacuum leak spots.

Compression test has been done hot and cold and readings are 150-160. And haven't thought about the cats, will source hopefully a stock one later alongside with that speed sensor.