89 Mustang engine bucks btwn 45 & 65 mph & lots of black smoke exhaust

I have a 4 cyl A code that sometimes bucks and loses power at around 45- 65 mph. I also get a lot of carbon thru the tailpipe. BUT, the plugs aren't
carboned up. It bucks so hard that I can sometimes hear the u-joints banging back and forth like the rear end is going forewards and back. I've done a complete tune up, checked pcv, egr, replaced the computer and checked timing. Also put in a new trans filter and changed the fluid.
Any advice or ideas? Thanks- Laura
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But it starts and idles okay, cold and warm?
I'd rather know the RPM's... and see if it's same rpm range in both OD and D On Acceleration or even when you hold (or try to hold) speed
Also.. does it have a MAF?
Check engine Light doesnt come on?
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Yes it starts ok and idles ok in cold and warm.
Haven't watched RPM's but the trans doesn't seem to be slipping. It does seem hesitant in OD, sometimes it engages at 45...sometimes at 50.
Nope, no MAF, it has B.MAP.
Check engine light hasn't come on.
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LauraK wrote:

I don't know if this will help but my friend had similar problem with her 2001, no check engine light either, but she went to autozone and they hooked it up for free and read the meter, and it was a sensor in the exhaust system. It was an 80$ part but it was very easily installed from a guy friend of hers so no added cost in labor. Do you think that might be the same for you? Hope it is nothing serious! Take Care, beth
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Unfortunately, the poster's 89 is an EEC-IV system. AutoZone will only read the 95-up OBD2 systems.
CJB

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CJB wrote:

You can BUY a perfectly acceptable EEC-IV digital reader for about $35. Then there's the cheap way:
http://www3.telus.net/neatcrap/eec4.gif
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