Good luck man, Lotts of people have little issues with these 2.5. They tend to run great for a long time and then wamooo. These 2.5 can be on the tricky side, to find lil gremlins in throtlebody, sensors, dist, fuel issues, CPU could all be cupruts. Firt check for good comp,fuel,spark. Make shure timing is TDC, my 87 has computer controlled fuel and timing. Open the hood at night and make shure theres no arching. Check your fuel presure with a gauge, My 87 is at 15 psi, newer might be differen't. If those all check out look at sensors or possible Vac leaks or cracked exahust manifold or bad gaskets. I have the same problems with my 87 and have done most of what what was said in the above paragraphs and still have a problem. My next thing to replace is the computer CPU. Good luck, the answers will come.