1987 Volvo 240 DL - Approx.120,000 miles ***Sat for 2 years***

I aquired a volvo in fair condition about 6 months ago, it was a rough start but I did drive the car temporarily for about 3 months with little problems. [The only major repair was a timing belt repacment with my Father]

Due to bad stickers the car has sat since April. Currently attempting to get it to pass emissions so I put a can of BG44k in the remaining half-tank of gas that was a little old. Then put another can in with a fresh tank and drove it out of town last weekend to run the fuel through.

When we started to reach higher rates of speed we noticed that the car would not engage in 4th gear. The overdrive light was ON on the dash and would not turn off. Poor car was almost screaming the whole way so we eased off and stayed in the right lane.

When I got back home I spoke with a motorhead friend of mine and my Dad [Dillon - Username on Brickboard]And they both thought to check the Overdrive relay first. So I removed the glove compartment, located the relay. I heard clicking in the relay, but it was not always responsive when I pressed the button on the shifter. It also got very hot, I assume the coil a/o contacters in the relay have gone bad... I will buy a new relay and hope that is the issue

But here is my doozie...

Since I was already screwing around with my car and I had about 1/3 of a tank left from the trip with BG44k I decided to let it sit and run for awhile. I turned on the heat and let it run for about 1.5hrs. Came back to check on it and my friend suggested to run the car WITHOUT the relay in it and see what it does. We started to drive the car and the engine would rev up, then down, then up... It would run then hesitate then return up... The throttle was not coughing and I was not fluttering the accelerator. I put the relay back in and it still ran that way. It almost seemed like a response issue of sorts either electricly or something... This is where I can't diagnose or figure out.

The only factors that were involved before this happened was that the car was a little hotter than normal, I've never let it idle that long and the relay was out of the car for some time...

Can someone please give me an idea of what to do to troubleshoot the issue or fix???? Please, thanks

-A Volvo Girl