A couple of weeks ago the 90 started acting weird. I first noticed it when I pulled from a stop sign and opened it up in the first 2 gears. Then it gave me a surging / hickup. I didn't think too much of it until it was happening a lot during one more short drive. It seems to be happening more frequently.
- It can be in any gear but mostly when I give it throttle and then let up to control my speed. When I let up and then go to give it more throttle there is nothing there yet it doesn't stall. What I've been doing is depress the clutch and give it a solid hit of throttle. Most of the time it happens when I let up on the throttle but at times it can be when I going to give it more.
- It idles fine. With the past cold days I've been letting it idle to warm up and then to see if it would stall or act up. But it is fine. I can blip the throttle to wide open and it seems normal.
- I noticed last night, that when it happened on an open part of road without traffic, I would depress the clutch and keep my foot in the same throttle position. It would dip to about 900 RPMs (normal idle) and after a brief moment the RPM's would pop up to about 3,000 - then drop, then go back, drop, and continue the cycle.
- I swapped the silver relays with a couple from AB (the black ones), swapped the coil, unplugged the MAF, after reading about the TPS and what it does I thought that "must be it" and bought one from AB. All things I changed one at a time then drove for a day to see what the effect would be.
I'm trying to get it so I can duplicate it at will but haven't gotten to it. But if I drive around enough it seems to eventually happen. What's weird is, I will get a time of normal running - like 10 minutes at a time. On the highway it seems to work fine too.
So - any ideas or any things I should check? I've been STFA under surging and a bad alternator pops up. With it being cold I've been running the fan more lately could that throw it off? What about driving around town and then using the blinker of all things? I have an appointment at the local garage that works on for tomorrow and I'd like to have a better idea of what it might be before I bring it in. Or at least be able to duplicate it at will.
Any help is very appreciated - thanks!