What could cause multiple TPS's to go bad? (S4 n/a)

[need RX7]

It all started when my FC got very hard to start, and when it did it could barely idle. I checked the resistance on the TPS and it was out of spec, and I couldn't adjust it back into spec so I decided to get a new one. I went and picked one up from a junkyard ($230 from mazdatrix? F that) I installed it and it also wouldn't get in spec. It didn't strike me as odd though, since it was sitting out in the open on a car with no hood for who knows how long. So I picked up another one from a different junkyard, long story short, another dud.
I finally went and bought one from a (supposedly) running car off a guy on RX7club. After receiving it, I was sure it would be the solution to all my problems. I was wrong once again, with all the adjustmen in the world, I can't get it under 2k ohms closed, and it immediately jumps to 8k at WOT (just like all the other ones). It does start though, but it has an odd pulsating idle and doesn't like to rev higher than 3k rpm.
I'm testing with a standard multimeter, with the leads stuck in the Black and Green leads on the TPS plug, with the TPS unplugged and a jumper wire in the initial set coupler.
So am I just having bad luck with buying parts, or is there something else wrong somewhere else? Or am I doing something wrong? I'm open to any suggestions, I just want to get this thing running correctly before the major snow comes

[need RX7]

It all started when my FC got very hard to start, and when it did it could barely idle. I checked the resistance on the TPS and it was out of spec, and I couldn't adjust it back into spec so I decided to get a new one. I went and picked one up from a junkyard ($230 from mazdatrix? F that) I installed it and it also wouldn't get in spec. It didn't strike me as odd though, since it was sitting out in the open on a car with no hood for who knows how long. So I picked up another one from a different junkyard, long story short, another dud.
I finally went and bought one from a (supposedly) running car off a guy on RX7club. After receiving it, I was sure it would be the solution to all my problems. I was wrong once again, with all the adjustmen in the world, I can't get it under 2k ohms closed, and it immediately jumps to 8k at WOT (just like all the other ones). It does start though, but it has an odd pulsating idle and doesn't like to rev higher than 3k rpm.
I'm testing with a standard multimeter, with the leads stuck in the Black and Green leads on the TPS plug, with the TPS unplugged and a jumper wire in the initial set coupler.
So am I just having bad luck with buying parts, or is there something else wrong somewhere else? Or am I doing something wrong? I'm open to any suggestions, I just want to get this thing running correctly before the major snow comes