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Hi Guys,
I have a 98 HX (5 speed) with about 200k miles. I just got the car about a month ago. It ran well when I got it, but it threw an EGR low flow code after a week or so. I cleaned out the very blocked EGR ports, cleaned the idle control valve, throttle body.

The problem I am having started, I think, after the cleaning. I am not sure though, since I was so new to the car. After the car has warmed up a stumble develops right as you are just rolling on the throttle after coasting, or just driving along with your foot just barely on the gas. It acts just like there is a dead spot on the TPS. This happens much more noticeably when the car is warmed up and has been moving slowly (i.e. under hood temps starting to get higher) It is not a violent buck, but it acts like fuel is being cut for just a second. This results in an annoying jerking as you roll on an off the throttle while driving in traffic. If you hold the throttle just in the perfect position with the clutch in it will rev up to about 1500 then cut out and drop back to about 600, then rev back to 1500. It will do this for as long as you hold the throttle in that certain spot.

So far I have done the following:
-new plugs, wires cap and rotor
-new pcv valve
-new air and fuel filter
-new tps set exactly at .45 volts at idle
-tried to burp and bleed the coolant as much as possible
-cleaned idle valve again and again
-check to make sure the EGR valve appeared to be closed all the way
-done the idle setting and relearn according to the honda PDF on this site
-checked for vac leaks all around the intake using carb cleaner to see if the idle was effected

I am at a loss on this one, the idle valve seems to work fine, the idle stabilized right where it should be, and you can hear the idle valve operating through the intake like it should. I don't want to rule out a coolant bubble, but I have tried several times to burp it and am not getting any more air out of it. I am set up to test most anything, I have a multimeter, mighty vac and an OBD scanner that also can read live data. The car runs perfect otherwise, gets amazing mileage, and throws no codes at all. Am I missing something else??
Thanks in advance.

 
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well the issue ended up being a crack in the manifold right from the o2 bung around the collector. I couldn't really tell it was leaking, but when I took the heat shield off i could see a good sized crack. I welded it back up and it seems to be running like it should now.

 
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this sounds very similar to a problem i am having. but i really dont know too much about cars. like, is the manifold the part after the intake/throttle, before it goes into the engine?

I start my car, and 3-5 minutes later, it starts to sputter and act like its starving for gas, as if I let off the gas. I can just tap the gas repeatedly, and it will continue to go, (throttle will temporarily work, in spurts), but if i hold the petal, it acts as if im letting go of the petal, and it sputters really bad. if i mash the petal down, i get one of two things, very horrible sounds (so i dont do this anymore.. learned the first time) or if i time it right, i get it to go with the higher RPM and it acts fine for a second, then gors back to the problem. and it acts like this until i pull over and let it idle and go through a little sputter fit, and then its fine... until i hit a bump, stop for a sign, or red light, then when i go again, it does it again. its really freaking me out, makes me wonder if I'm going to make it to work everyday.

I have seen many issues on these forums that are almost similar, but not quite what i am experiencing. I've read peoples posts saying everything from change the plugs/wires/distributor, to vacuum leaks, to air filter, to fuel pump/filter/injectors, to sensors, to fuses, to head gasket. and I really just dont have the money to go down the whole list, especially if i do it in the wrong order, and fix it on the last one!

I have replaced the fuel filter, air filter, and run injector cleaner through it several times, got new plugs, and it hasnt been too terribly long since i had gotten a new head gasket

Someone please help! Thank you in advance