'87 Supra N/A stumbling problem

[daddsun]

I have searched this forum looking for an answer but, couldn't find a similar topic. I have an '87 Supra N/A with 148,xxx miles on it and it has a stumbling problem which feels like a fuel cut which happens at varied throttle positions as well as when backing off of the throttle and it happens intermittently to make it more frustrating.
I have installed the following since I purchased it from the original owner about nine months ago:
New Toyota valve cover gaskets, NGK spark plugs, NGK spark plug wires (the original sumitomo's from '87 were still on it at 146k), Toyota dist. cap/rotor, Toyota air filter and fuel filter (the original was still present).
This past weekend I installed the Hose Techniques vacuum lines (being careful to use the thick walled in the intake manifold area). After having done all of this it still has the stumbling problem as it has since before any of these regular maintenance items were replaced. I also noticed that the T-pipe on the valve cover gaskets has a couple of bad hoses connecting it to the valve covers and that was the next thing I wanted to replace.
Any ideas would be greatly appreciated and here is a pic of the patient:

[NDBoost]

did you check the TPS to make sure its working correctly? Mine did something similiar come to find out the TPS's spring inside the sensor was frozen and didnt work correctly. By the way where are you getting the T piping for the valve covers to Tbody? I need to replace those rubber boots on mine as well

[daddsun]

I haven't checked that yet; where is the TPS located? Regarding the T piping I am going to try the Toyota dealer first to see if they have the hoses and clamps and if that turns out to be too expensive the next step is to order some 10mm hose from Hose Techniques (the kit didn't come with any 10mm hose).
Thanks for the tip.

[NDBoost]

no problem TPS is located on the throttle body facing away from the cockpit its a little black round thing with a wire connected to the right side (as your looking at the car) should be near all the hosing that goes into the TB. Look on ebay for a Toyota SUPRA TPS to get pics

[NDBoost]

oh yeah and another thing i forgot to mention the TPS's have to be calibrated and adjusted.
What you do is mark the location of the TPS on the Throttle body with white out, take it off and try to turn the spring if it doesnt snap back then the spring is frozen and you need a new TPS. the other thing you need to test for is that the contacts inside are workig properly. Basically all it is is a potentiometer that increases resistance and the ecu measures that resistance and compares it with a chart.

Get a volt meter and get the proper resistance #'s i dont have the manual in front of me else id give them to you. Then test the TPS with it on the TB. After replacing TB make sure to adjust the TPS to the correct settings or else its pointless.

This was the 1st thing i did to my car, increased my gas mileage back up to stock 17mpg. I was getting about 7-8mpg before replacing the TPS. Cost me like $15 shipped on ebay for the TPS used. Dont get one from the dealer their like $100 new and its practically a rip.

[daddsun]

Great! Thanks again. If you have to replace the TPS are they expensive? I almost bought a project '87 Supra a few years ago and someone had removed the TPS and I think the rumor was that it cost like $400 and was a dealer only part? Hopefully mine has the same problem that yours did.

[daddsun]

Okay great! After all the money I have spent on this car in a relatively short period of time if the TPS is totally screwed another $100 wouldn't be too bad. I'll let you know what I find out about the T pipe at the dealer.

[NDBoost]

cool please do

[daddsun]

I have the factory service manual and I'll look up the TPS this afternoon.

[daddsun]

Sorry to resurrect this thread but, my schedule has not allowed for much Supra time lately. The Z cars have been hogging time since they are old and cranky. The Supra ended up getting a new TPS from the dealer parts dept.

The first time out the parts person ordered the wrong one (180 degrees out) so that went back and the right piece was delivered a week later. No big deal since I was ordering a bunch of parts for my cousin's '95 Camry (T-belt w/ all the goodies). While I was at I ordered the T-pipe hoses and they cost about $48 (the molded hose at the front of the engine was about $30 and since everything that passes air has been changed I figured what the hell. Since I was going all out I got the last known tan leather shift knob in existence and that was about $120! At 150k miles it seems to be happy although my father has been driving it for about two months now and recently he stated that she won't start (over the phone it sounds like a bad starter solenoid) so I guess it wants more attention?