VX hesitation

[mrmcg1]

Hello, I have posted this question on another Honda site (and have gotten some good information) but someone suggested that this is a better forum for a VX question. Question as follows: I have a '92 VX that hesitates badly once it warms up (runs fine when cold). I purchased this car recently, the hesitation was pre-existing. We have done a full tune up, including plugs and wires, fuel filter, air filter, oil filter, oil etc... This didn't help.
I have a spare engine which we have used to swap out sensors and parts. We have swapped out all the sensors on the intake manifold, the distributor, and the ECU, none of this has helped.
The check engine light has never come on, so there are no codes to help diagnose.
It has a 5 wire O2 sensor, which looks newer, I have not confirmed whether it is an NGK or otherwise (have read that Bosch can be problematic). Any help or suggestions on how to correct this problem would be appreciated

[GasSavers_landon]

First suspects would be coolant temp sensor & o2 sensor.

[1993CivicVX]

Based on my VX experience, this indicates bad o2 sensor: I have a '92 VX that hesitates badly once it warms up (runs fine when cold).

There's no reason to think both o2 sensors are tired. How many miles on the spare engine? Was the hesitation the same with both o2 sensors or was it slightly worse with one or the other?

[suspendedhatch]

He didn't try a different O2 sensor.

There's a big topic above this one with almost the same title.

Tell baller status I said "what's up".

[mrmcg1]

My spare engine did not come with an O2 sensor. We are going to try testing the existing sensor in the next few days to see if it is in spec. The mileage on both engines is a unknown.

[socalsupehero]

I had a similar problem with my vx engine. Check the tps sensor. should register +.5v with engine off and throttle completely closed, and +4.5-4.6v at wot. Adjust the sensor until you get the correct values.

[mrmcg1]

I looked at the O2 sensor today. It says "L1H1 Japan", which I assume is the OEM NGK/NTK. The mechanic I am working with was not sure how to test it, or what was considered "in spec", any help on that would be appreciated. We will also test the TPS sensor as suggested. Thanks

[GasSavers_mango]

I had a bad hesitation problem that turned out to be the result of a dirty throttle body. My mechanic cleaned the throttle body and that did the trick.

[roadsterbum]

I also had a bad hesitation that turned out to be severely retarded timing. It may sound stupid, but it's easy enough to check and cross off your list of potential reasons.

[mrmcg1]

We cleaned the throttle body and checked the timing, they didn't do the trick. Finally purchased a new O2 sensor (NTK L1H1 for $99 from www.autopartsdirecttoyou.com), it seems to have worked. There is still some subtle hesitation but I think I can live with it. Now I need a road trip to see what the mileage is like.
Another question: what should the engine idle at when warmed up? Mine seems to idle at about 500 rpms or lower, it has not stalled yet but feels like it wants to.