First post here, Thanks for your interest and any advice.

98 Accord 4cyl auto sedan 250k

Had check engine light on steady

pulled codes at AZone

upstream O2, misfire, vacuum leak, and shift issue code for trans

replaced O2

Misfire was ( I believe) oil in a plug galley, which was completely full. replaced all seals and gaskets including distributor O-ring and spark plugs OEM

It did shift poorly initially but was cleaned up nearly 100% by doing the drain 3qts and replace 3qts with genuine Honda trans oil, have done this twice need to do one more time. I know trans was rebuilt but not sure when, but initial draining had good color and no burnt odor

Found crack on intake hose pipe in between MAS and throttle body which I used JB weld

The car burns no oil, and runs buttery smooth. Got nearly 400 miles on tank as fuel light came on

BUT on occasion rain or shine, cold or hot when I first start it its like it stumbles horrible (like lawn mower on chock minus smoke from exhaust) for about 5-10 seconds then it quickly clears its self out idles very smooth meaning if I had a glass of water sitting in cup holder there would be no ripples in the water.

This morning it started ruff, stumbled longer than usual maybe 10 sec, then immediately started slowly flashing CEL. But again it cleared right up runs very smooth, gets great fuel economy, shifts smooth, all fluids good. I just ordered new plug wires online, and going to replace plugs again. I'm thinking if that does'nt clear things up then I'll order new distributor (whole assembly)

The only thing that comes to mind is I did use the chevron w techron fuel treatment because of the occasional stumble, and I'm about half way through the tank that I treated.

 

You may want to check that your IACV is working properly. IIRC on '98-02 there is no longer a FITV just the IACV. If it is gummed up, sticking, or fouled with soot it may not be able to properly control the cold idle speed.

Find out what the CEL code is now present. And post the actual code.
Although OBDII is a better system for self diagnostics, just because a code is triggered does not always mean that the code set is the problem.

 

When I go home sunday, I'll pull the codes again and post...thanks

 

I removed throttle body, plenum, and IACV. Bought new Honda IACV gasket, and plenum gasket but used advance auto for throttle body gasket. Also replaced vacuum line on IAC and one coolant line , the one that is closest to passenger side. Cleaned IAC reinstalled everything and it was perfect for two days. Now its back to the same, and loosing large amounts of coolant, around 1/4 gal in 40 mile trip. I dont see any leaks, dont see any water on dip stick or inside valve cover or under valve cover cap and no smoke from tail pipe. Pulled plugs and they look fine too. I guess from here I'm going to order new IAC and put new coolant lines everywhere and pressure test the system. Forgot to mention I did undo negative terminal on batt. prior to work and CEL didn't come on till it did that extremely rough start where it'll start run on what feels like 1 cyl. then stalls and I have to hold gas down to start it, runs like poo for 8-10 seconds then flashing CEL, then runs perfect around 750 rpm with no fluctuations regardless of having it in gear or A/C on. Any thoughts or comments are welcomed

 

Before ordering any new parts, do a compression test on the cylinders and locate that coolant leak. You will need to fix the current problem, the loss of coolant may be causing the erratic behavior currently.

 

I am setting that compression test for this thursday, I will post any findings and numbers afterwards. Thanks for the help!