Throttle body repair/replace question

[slowride]

Recently picked up an 03 Tahoe with 133k and the 5.3 engine. It had been parked for a couple months before I got it. Noticed when driving it home I would sometimes feel like it was going to stall out at stoplights and I would have to put it in neutral and feather the gas to smooth it out. Also has what seems to me to be a somewhat drawn out 1-2 shift. Stopped and put a can of seafoam in the gas on the way which seemed to help the idle by the time I drove it an hour and half home.
The idle issue started to come back from time to time and the shifting issue stayed the same. Was worried the trans was on the way out until I read the throttle body could cause both issues if it was going bad. Took it off and cleaned it, no change. Pulled the one off my 06 which runs fine and swapped it on, worked great no more idle or shifting issues. So now I figure I just need another throttle body assembly for the 03. Found a guy parting out an 06 truck and got the throttle body off it. Cleaned it up and put it on. Did the relearn steps. Now when I start the tahoe, or just turn the key on, there is an intermittent tap you can hear and feel in it which seems to be from the black plastic throttle sensor part. Doesnt run as smooth at idle as it did with the one off my other tahoe, doesnt seem to stall but feels like the engine has a miss. Trans shifts a little better than with the old unit on it.
So now Im thinking this used one I got is no good? I dont know if I should just get a new throttle body assembly or should I just try to replace the throttle position sensor part that is rivited on it? Any suggestions here would be appreciated, thanks

 

[Doubeleive]

the maf (mass airflow sensor) can have a effect on all that as well, have you cleaned it or replaced it?

 

[TxDrewski]

Are you getting any CEL?

 

[slowride]

No CEL and yes I did clean the MAF sensor too while I had stuff apart. Also FWIW, I got all the maintenance records with it since the town bought it new and the trans has never been serviced. They did however have the local chevy dealer install new fuel pump, filter, plugs and wires in the last 10k miles. I plan on changing the trans filter soon.

 

[TxDrewski]

If it ran fine with your other working TB, Id assume you got a bad used unit and Id go that route. Also, you may have fuel injector issues due from the truck sitting up. Ive had that happen before with my 04

 

[TxDrewski]

Sea foam the system VIA the brake booster, see what happens after.

 

[cmc76]

If you cleaned the tb, did you push on the butterfly at all.
Try a tb relearn. I forget the exact process. Google knows though

 

[slowride]

Yeah I did open and close the butterfly when I did a cleaning, on the old one, the one off my 06, and the used one I bought. That ticking or popping coming from the used one I got has me stumped, couldnt find anything online about that just lots of posts saying it was probably coming from somewhere else but I know its coming from the sensor housing side on it. Being that it ran fine with swapping on the good unit from my 06 without doing anything else, I did do the relearn procedure each time I swapped one, it seems like the old and the "new" used ones are bad. I dont know if I should just get a whole new assembly or if I should try to take the throttle position sensor part off of it and replace that. I see dorman sells just that piece you can bolt back on after you drill out the rivets on the old one. Anybody ever try that?

 

[TxDrewski]

Whats the price difference on just doing the TPS vs the whole thing?
Id still maybe run seafoam through the booster and see what happens. Does sound like you have essentially 2 bad TBs

 

[slowride]

I see just the throttle position sensor piece from dorman for like $45 and I can get a whole new hitachi, supposedly oem, assembly for about $120. Didnt know if that would turn out like just trying to replace the fuel pump in the hanger assembly where you might be better off replacing the whole unit where its all factory assembled