Black smoke from tailpipe, loss of power, anyone know?

One possible cause - head gasket coolant leak also cauing plug fouling.

Loss of 5-volt reference can be caused by an open in the wire (check the continuity of the wire from computer to TPS) OR a short in the harness or another sensor that uses the same reference wire. White smoke off the engine or out the tailpipe? Loss of 5-volts would never cause white smoke out the tailpipe

To much fuel being dumped. Check vacuum lines for leaks to start. Could be stuck injectors.

If the end of the sparkplug is back, indicates carbon build up. Buy a compression tester, way cheaper and easier, although I'm not sure if it is a head gasket. What color is the smoke that comes out of the tailpipe, a greyish blueish or is it black? Does the engine shudder? Where the spark plugs themselves changed and gapped correctly? It may be detonation also.

defective catalytic convertor. It may be plugged up.Make sure ALL the exhaust line from intake manifold(at engine block) to final exhaust pipe are not clogged up.You have reverse exhaust pressure going back towards engine manifold.

Black smoke indicates no air, check your air filter, if you have done that and it is ok, check the PCV valve. Thats about all that I can suggest. Hope that helps.

seems like you are leaking antifreeze inside your engine have it checked white smoke usually means antifreeze

A puff of smoke when you start up indicates worn valve seals.That's why all your work didn't fix the problem and it doesn't show a code. It's a pain in the --- job that requires some specialized tools so I guess it depends on how bad it bugs you,if oyu want to fix it.

hi nishga
im dave; hope i can help

First you need to determine if it is actually black smoke or if it is blue smoke. There are three colors of smoke that can come from the tailpipe. It is not white smoke obviously because that is easily differentiated from blue or black and generally indicates water or antifreeze leaking past the head gasket and into the compression area of the motor. White smoke is the steam of the water/antifreeze being emitted

Blue smoke is caused by engine oil entering the cylinder area and being burned along with the fuel air mixture. As with white smoke, just a small drop of oil leaking into the cylinder can produce blue smoke out the tailpipe. Blue smoke is more likely in older or higher mileage vehicles than newer cars with fewer miles. The car has many seals, gaskets, and o-rings that are designed to keep the engine oil from entering the cylinder, and one of them has failed. If too much oil leaks into the cylinder and fouls the spark plugs, it will cause a misfire(engine miss) in that cylinder, and the spark plug will have to be replaced or cleaned of the oil. Using thicker weight engine oil or an oil additive designed to reduce oil leaks might help reduce the amount of oil leaking into the cylinder.

Black smoke is caused by excess fuel that has entered the cylinder area and cannot be completely burned. Another term for excess fuel is "running rich". Poor fuel mileage is also a common complaint when black smoke comes out of the tailpipe. Black smoke out the tailpipe is the least cause for alarm. Excess fuel will usually effect engine performance, reduce fuel economy, and produce a heavy fuel odour in the engine compartment. Some of the causes of excess fuel are a carburetor that is out of adjustment which is not likely unless you have installed an aftermarket carburated system on your non-carburated car, a faulty fuel pump, a leaky fuel injector, or a faulty engine computer or emissions sensor. If black smoke is present, check the engine oil to make sure excess fuel has not contaminated it. Do not start the engine if a heavy, raw fuel smell can be detected in the engine oil. Check the above mentioned systems and after detecting the trouble replace the faulty parts and then the engine oil and filter.

What color smoke out of the tailpipe ? Black - running rich , too much fuel or not enough air . Blue smoke - burning oil , piston rings valve seales , white smoke could be two different thing's - coolant in the cylinders or fuel going stright through the cylinder out the tailpipe . No combustion .
Check engine light on ? Have you replaced plugs an plug wires ,air filter , any engine sensors - TPS - MAP - MAF etc.... How many miles on the vehicle ? 1988 model - engine worn out ?